[syzbot] [fbdev?] KASAN: slab-out-of-bounds Read in fbcon_prepare_logo

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d082ecbc71e9 Linux 6.14-rc4
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=100c97a4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1635bf4c5557b92
dashboard link: https://syzkaller.appspot.com/bug?extid=0c815b25cdb3678e7083
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/323a5d590eec/disk-d082ecbc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7c4b6e33fd9/vmlinux-d082ecbc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c518bbd55334/bzImage-d082ecbc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0c815b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in scr_memcpyw include/linux/vt_buffer.h:38 [inline]
BUG: KASAN: slab-out-of-bounds in fbcon_prepare_logo+0xa15/0xc80 drivers/video/fbdev/core/fbcon.c:614
Read of size 256 at addr ffff888033e96f60 by task syz.0.317/7285

CPU: 1 UID: 0 PID: 7285 Comm: syz.0.317 Not tainted 6.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0xc3/0x670 mm/kasan/report.c:521
kasan_report+0xd9/0x110 mm/kasan/report.c:634
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189
__asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105
scr_memcpyw include/linux/vt_buffer.h:38 [inline]
fbcon_prepare_logo+0xa15/0xc80 drivers/video/fbdev/core/fbcon.c:614
fbcon_init+0xd41/0x1890 drivers/video/fbdev/core/fbcon.c:1146
visual_init+0x31d/0x620 drivers/tty/vt/vt.c:1011
do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3831
vt_bind drivers/tty/vt/vt.c:3987 [inline]
store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059
dev_attr_store+0x55/0x80 drivers/base/core.c:2439
sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:139
kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0x5ae/0x1150 fs/read_write.c:679
ksys_write+0x12b/0x250 fs/read_write.c:731
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f44b6f8d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f44b7dc3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f44b71a5fa0 RCX: 00007f44b6f8d169
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f44b700e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f44b71a5fa0 R15: 00007ffee813d3a8
</TASK>

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888033e94340 pfn:0x33e94
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000040 0000000000000000 dead000000000122 0000000000000000
raw: ffff888033e94340 0000000000000000 00000001ffffffff 0000000000000000
head: 00fff00000000040 0000000000000000 dead000000000122 0000000000000000
head: ffff888033e94340 0000000000000000 00000001ffffffff 0000000000000000
head: 00fff00000000002 ffffea0000cfa501 ffffffffffffffff 0000000000000000
head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x140dc0(GFP_USER|__GFP_COMP|__GFP_ZERO), pid 7285, tgid 7284 (syz.0.317), ts 193263994848, free_ts 193235941647
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1551
prep_new_page mm/page_alloc.c:1559 [inline]
get_page_from_freelist+0xfce/0x2f80 mm/page_alloc.c:3477
__alloc_frozen_pages_noprof+0x221/0x2470 mm/page_alloc.c:4739
__alloc_pages_noprof+0xb/0x1b0 mm/page_alloc.c:4773
__alloc_pages_node_noprof include/linux/gfp.h:265 [inline]
alloc_pages_node_noprof include/linux/gfp.h:292 [inline]
___kmalloc_large_node+0x84/0x1b0 mm/slub.c:4239
__kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:4266
__do_kmalloc_node mm/slub.c:4282 [inline]
__kmalloc_noprof.cold+0xc/0x61 mm/slub.c:4306
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1037 [inline]
vc_do_resize+0x1e3/0x10f0 drivers/tty/vt/vt.c:1174
vc_resize include/linux/vt_kern.h:49 [inline]
fbcon_init+0xd1d/0x1890 drivers/video/fbdev/core/fbcon.c:1143
visual_init+0x31d/0x620 drivers/tty/vt/vt.c:1011
do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3831
vt_bind drivers/tty/vt/vt.c:3987 [inline]
store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059
dev_attr_store+0x55/0x80 drivers/base/core.c:2439
sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:139
kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0x5ae/0x1150 fs/read_write.c:679
page last free pid 7285 tgid 7284 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1127 [inline]
free_frozen_pages+0x6db/0xfb0 mm/page_alloc.c:2660
__folio_put+0x32a/0x450 mm/swap.c:112
vc_do_resize+0xe31/0x10f0 drivers/tty/vt/vt.c:1194
vc_resize include/linux/vt_kern.h:49 [inline]
fbcon_startup+0x406/0xb70 drivers/video/fbdev/core/fbcon.c:997
do_bind_con_driver.isra.0+0x207/0xbf0 drivers/tty/vt/vt.c:3794
vt_bind drivers/tty/vt/vt.c:3987 [inline]
store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059
dev_attr_store+0x55/0x80 drivers/base/core.c:2439
sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:139
kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0x5ae/0x1150 fs/read_write.c:679
ksys_write+0x12b/0x250 fs/read_write.c:731
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff888033e96f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888033e96f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888033e97000: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
^
ffff888033e97080: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
ffff888033e97100: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
==================================================================


---
This report is generated by a bot. It may contain errors.
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#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: d082ecbc71e9 Linux 6.14-rc4
git tree: upstream

console output: https://syzkaller.appspot.com/x/log.txt?x=14f56db0580000

kernel config: https://syzkaller.appspot.com/x/.config?x=b1635bf4c5557b92
dashboard link: https://syzkaller.appspot.com/bug?extid=0c815b25cdb3678e7083
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=172e77f8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/323a5d590eec/disk-d082ecbc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7c4b6e33fd9/vmlinux-d082ecbc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c518bbd55334/bzImage-d082ecbc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0c815b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in scr_memcpyw include/linux/vt_buffer.h:38 [inline]
BUG: KASAN: slab-out-of-bounds in fbcon_prepare_logo+0xa15/0xc80 drivers/video/fbdev/core/fbcon.c:614

Read of size 256 at addr ffff888032edef60 by task syz.2.2428/8600

CPU: 0 UID: 0 PID: 8600 Comm: syz.2.2428 Not tainted 6.14.0-rc4-syzkaller #0

RIP: 0033:0x7fb44418d169

Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007ffe52f027e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fb4443a5fa0 RCX: 00007fb44418d169

RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000003

RBP: 00007fb44420e2a0 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007fb4443a5fa0 R14: 00007fb4443a5fa0 R15: 0000000000000003

</TASK>

The buggy address belongs to the physical page:

page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32edc

head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000040 0000000000000000 dead000000000122 0000000000000000

raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000

head: 00fff00000000040 0000000000000000 dead000000000122 0000000000000000

head: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
head: 00fff00000000002 ffffea0000cbb701 ffffffffffffffff 0000000000000000

head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 2, migratetype Unmovable, gfp_mask 0x140dc0(GFP_USER|__GFP_COMP|__GFP_ZERO), pid 8600, tgid 8600 (syz.2.2428), ts 463971995066, free_ts 463963903452

page last free pid 8600 tgid 8600 stack trace:

reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1127 [inline]
free_frozen_pages+0x6db/0xfb0 mm/page_alloc.c:2660
__folio_put+0x32a/0x450 mm/swap.c:112
vc_do_resize+0xe31/0x10f0 drivers/tty/vt/vt.c:1194
vc_resize include/linux/vt_kern.h:49 [inline]
fbcon_startup+0x406/0xb70 drivers/video/fbdev/core/fbcon.c:997
do_bind_con_driver.isra.0+0x207/0xbf0 drivers/tty/vt/vt.c:3794
vt_bind drivers/tty/vt/vt.c:3987 [inline]
store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059
dev_attr_store+0x55/0x80 drivers/base/core.c:2439
sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:139
kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0x5ae/0x1150 fs/read_write.c:679
ksys_write+0x12b/0x250 fs/read_write.c:731
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:

ffff888032edef00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888032edef80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888032edf000: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
^
ffff888032edf080: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
ffff888032edf100: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
==================================================================


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 4b290aae788e Merge tag 'sysctl-6.17-rc1' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10ff8834580000
kernel config: https://syzkaller.appspot.com/x/.config?x=eb654b6c0c63cccc

dashboard link: https://syzkaller.appspot.com/bug?extid=0c815b25cdb3678e7083
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=134389bc580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17a82ca2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6d83c5020884/disk-4b290aae.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/91441dce0745/vmlinux-4b290aae.xz
kernel image: https://storage.googleapis.com/syzbot-assets/55d2e063b8a3/bzImage-4b290aae.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0c815b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in scr_memcpyw include/linux/vt_buffer.h:38 [inline]

BUG: KASAN: slab-out-of-bounds in fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:618
Read of size 256 at addr ffff8880331da860 by task syz.0.17/5996

CPU: 0 UID: 0 PID: 5996 Comm: syz.0.17 Not tainted 6.16.0-syzkaller-04405-g4b290aae788e #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025

Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120

print_address_description mm/kasan/report.c:378 [inline]
print_report+0xcd/0x630 mm/kasan/report.c:482
kasan_report+0xe0/0x110 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:189

__asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105
scr_memcpyw include/linux/vt_buffer.h:38 [inline]

fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:618
fbcon_init+0xd77/0x1900 drivers/video/fbdev/core/fbcon.c:1150
visual_init+0x31d/0x620 drivers/tty/vt/vt.c:1019
do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3915
vt_bind drivers/tty/vt/vt.c:4071 [inline]
store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4143
dev_attr_store+0x55/0x80 drivers/base/core.c:2437
sysfs_kf_write+0xef/0x150 fs/sysfs/file.c:145
kernfs_fop_write_iter+0x354/0x510 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x6c4/0x1150 fs/read_write.c:686
ksys_write+0x12a/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f580578e9a9

Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007ffce73cfbb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f58059b5fa0 RCX: 00007f580578e9a9
RDX: 0000000000000081 RSI: 00002000000001c0 RDI: 0000000000000004
RBP: 00007f5805810d69 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007f58059b5fa0 R14: 00007f58059b5fa0 R15: 0000000000000003
</TASK>

The buggy address belongs to the object at ffff8880331da000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 96 bytes to the right of
allocated 2048-byte region [ffff8880331da000, ffff8880331da800)

The buggy address belongs to the physical page:

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x331d8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0

flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)

page_type: f5(slab)
raw: 00fff00000000040 ffff88801b842000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b842000 dead000000000122 0000000000000000
head: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000cc7601 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008

page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5996, tgid 5996 (syz.0.17), ts 103546222970, free_ts 103072976762
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
prep_new_page mm/page_alloc.c:1712 [inline]
get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
__alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
alloc_slab_page mm/slub.c:2451 [inline]
allocate_slab mm/slub.c:2619 [inline]
new_slab+0x23b/0x330 mm/slub.c:2673
___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
__slab_alloc_node mm/slub.c:4024 [inline]
slab_alloc_node mm/slub.c:4185 [inline]
__do_kmalloc_node mm/slub.c:4327 [inline]
__kmalloc_noprof+0x2f2/0x510 mm/slub.c:4340
kmalloc_noprof include/linux/slab.h:909 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
vc_do_resize+0x1de/0x10e0 drivers/tty/vt/vt.c:1182
vc_resize include/linux/vt_kern.h:49 [inline]
fbcon_startup+0x427/0xba0 drivers/video/fbdev/core/fbcon.c:1001
do_bind_con_driver.isra.0+0x20a/0xbf0 drivers/tty/vt/vt.c:3878
vt_bind drivers/tty/vt/vt.c:4071 [inline]
store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4143
dev_attr_store+0x55/0x80 drivers/base/core.c:2437
sysfs_kf_write+0xef/0x150 fs/sysfs/file.c:145
kernfs_fop_write_iter+0x354/0x510 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x6c4/0x1150 fs/read_write.c:686
page last free pid 5947 tgid 5947 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1248 [inline]
__free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4148 [inline]
slab_alloc_node mm/slub.c:4197 [inline]
__do_kmalloc_node mm/slub.c:4327 [inline]
__kmalloc_noprof+0x1d4/0x510 mm/slub.c:4340
kmalloc_noprof include/linux/slab.h:909 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
fib6_info_alloc+0x40/0x160 net/ipv6/ip6_fib.c:155
ip6_route_info_create+0x14c/0x870 net/ipv6/route.c:3811
ip6_route_add.part.0+0x22/0x1d0 net/ipv6/route.c:3940
ip6_route_add+0x45/0x60 net/ipv6/route.c:3937
addrconf_prefix_route+0x2fd/0x510 net/ipv6/addrconf.c:2487
inet6_addr_add+0x589/0x960 net/ipv6/addrconf.c:3052
inet6_rtm_newaddr+0x1619/0x1c70 net/ipv6/addrconf.c:5058
rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6944
netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x58a/0x850 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896

Memory state around the buggy address:

ffff8880331da700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880331da780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880331da800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff8880331da880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880331da900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

[syzbot]

> #syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

want either no args or 2 args (repo, branch), got 1

> 4b290aae788e06561754b28c6842e4080957d3f7

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-out-of-bounds Read in fbcon_prepare_logo

==================================================================
BUG: KASAN: slab-out-of-bounds in scr_memcpyw include/linux/vt_buffer.h:38 [inline]
BUG: KASAN: slab-out-of-bounds in fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:618

Read of size 256 at addr ffff88802ad9b860 by task syz.0.17/6602

CPU: 0 UID: 0 PID: 6602 Comm: syz.0.17 Not tainted 6.16.0-syzkaller-04405-g4b290aae788e-dirty #0 PREEMPT(full)

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xcd/0x630 mm/kasan/report.c:482
kasan_report+0xe0/0x110 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:189
__asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105
scr_memcpyw include/linux/vt_buffer.h:38 [inline]
fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:618

fbcon_init+0x118d/0x1920 drivers/video/fbdev/core/fbcon.c:1150
visual_init+0x320/0x620 drivers/tty/vt/vt.c:1019

do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3915
vt_bind drivers/tty/vt/vt.c:4071 [inline]
store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4143

dev_attr_store+0x58/0x80 drivers/base/core.c:2437

sysfs_kf_write+0xef/0x150 fs/sysfs/file.c:145
kernfs_fop_write_iter+0x354/0x510 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x6c4/0x1150 fs/read_write.c:686
ksys_write+0x12a/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7f988878e9a9

Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007f9889579038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f98889b5fa0 RCX: 00007f988878e9a9

RDX: 0000000000000081 RSI: 00002000000001c0 RDI: 0000000000000004

RBP: 00007f9888810d69 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 0000000000000000 R14: 00007f98889b5fa0 R15: 00007ffc350333d8
</TASK>

Allocated by task 6325:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:260 [inline]
__do_kmalloc_node mm/slub.c:4328 [inline]
__kmalloc_noprof+0x223/0x510 mm/slub.c:4340
kmalloc_noprof include/linux/slab.h:909 [inline]
sk_prot_alloc+0x1a8/0x2a0 net/core/sock.c:2247
sk_alloc+0x36/0xc20 net/core/sock.c:2303
__netlink_create+0x5e/0x2c0 net/netlink/af_netlink.c:628
__netlink_kernel_create+0xed/0x750 net/netlink/af_netlink.c:2020
netlink_kernel_create include/linux/netlink.h:62 [inline]
nl_fib_lookup_init net/ipv4/fib_frontend.c:1438 [inline]
fib_net_init net/ipv4/fib_frontend.c:1644 [inline]
fib_net_init+0x26d/0x3f0 net/ipv4/fib_frontend.c:1629
ops_init+0x1df/0x5f0 net/core/net_namespace.c:138
setup_net+0x1ff/0x510 net/core/net_namespace.c:442
copy_net_ns+0x2a6/0x5f0 net/core/net_namespace.c:574
create_new_namespaces+0x3ea/0xa90 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0xc0/0x1f0 kernel/nsproxy.c:218
ksys_unshare+0x45b/0xa40 kernel/fork.c:3124
__do_sys_unshare kernel/fork.c:3195 [inline]
__se_sys_unshare kernel/fork.c:3193 [inline]
__x64_sys_unshare+0x31/0x40 kernel/fork.c:3193

do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6332:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2381 [inline]
slab_free mm/slub.c:4643 [inline]
kfree+0x2b4/0x4d0 mm/slub.c:4842
sk_prot_free net/core/sock.c:2286 [inline]
__sk_destruct+0x740/0x980 net/core/sock.c:2381
sk_destruct+0xc2/0xf0 net/core/sock.c:2409
__sk_free+0xf4/0x3e0 net/core/sock.c:2420
sk_free+0x6a/0x90 net/core/sock.c:2431
deferred_put_nlk_sk+0xc9/0x110 net/netlink/af_netlink.c:716
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
rcu_core+0x79c/0x14e0 kernel/rcu/tree.c:2832
handle_softirqs+0x219/0x8e0 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0x109/0x170 kernel/softirq.c:680
irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1050
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

Last potentially related work creation:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:548
__call_rcu_common.constprop.0+0xa5/0xa10 kernel/rcu/tree.c:3094
netlink_release+0x12f4/0x2020 net/netlink/af_netlink.c:798
__sock_release net/socket.c:647 [inline]
sock_release+0x8e/0x1d0 net/socket.c:675
netlink_kernel_release+0x4e/0x60 net/netlink/af_netlink.c:2080
nl_fib_lookup_exit net/ipv4/fib_frontend.c:1447 [inline]
fib_net_exit+0x40/0x80 net/ipv4/fib_frontend.c:1668
ops_exit_list net/core/net_namespace.c:200 [inline]
ops_undo_list+0x2eb/0xab0 net/core/net_namespace.c:253
cleanup_net+0x408/0x890 net/core/net_namespace.c:686
process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3321 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
kthread+0x3c2/0x780 kernel/kthread.c:464
ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88802ad9b000

which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 96 bytes to the right of

allocated 2048-byte region [ffff88802ad9b000, ffff88802ad9b800)

The buggy address belongs to the physical page:

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2ad98

head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0

anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b842000 0000000000000000 dead000000000001

raw: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000

head: 00fff00000000040 ffff88801b842000 0000000000000000 dead000000000001

head: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000

head: 00fff00000000003 ffffea0000ab6601 00000000ffffffff 00000000ffffffff

head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5925, tgid 5925 (syz-executor), ts 92458486289, free_ts 63680726622

set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
prep_new_page mm/page_alloc.c:1712 [inline]
get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
__alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
alloc_slab_page mm/slub.c:2451 [inline]
allocate_slab mm/slub.c:2619 [inline]
new_slab+0x23b/0x330 mm/slub.c:2673
___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
__slab_alloc_node mm/slub.c:4024 [inline]
slab_alloc_node mm/slub.c:4185 [inline]
__do_kmalloc_node mm/slub.c:4327 [inline]
__kmalloc_noprof+0x2f2/0x510 mm/slub.c:4340
kmalloc_noprof include/linux/slab.h:909 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]

ops_init+0x77/0x5f0 net/core/net_namespace.c:128
setup_net+0x1ff/0x510 net/core/net_namespace.c:442
copy_net_ns+0x2a6/0x5f0 net/core/net_namespace.c:574
create_new_namespaces+0x3ea/0xa90 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0xc0/0x1f0 kernel/nsproxy.c:218
ksys_unshare+0x45b/0xa40 kernel/fork.c:3124
__do_sys_unshare kernel/fork.c:3195 [inline]
__se_sys_unshare kernel/fork.c:3193 [inline]
__x64_sys_unshare+0x31/0x40 kernel/fork.c:3193

do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94

page last free pid 5666 tgid 5666 stack trace:

reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1248 [inline]
__free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4148 [inline]
slab_alloc_node mm/slub.c:4197 [inline]

kmem_cache_alloc_noprof+0x1cb/0x3b0 mm/slub.c:4204
getname_flags.part.0+0x4c/0x550 fs/namei.c:146
getname_flags+0x93/0xf0 include/linux/audit.h:322
user_path_at+0x24/0x60 fs/namei.c:3126
do_faccessat+0x139/0xba0 fs/open.c:493
__do_sys_access fs/open.c:552 [inline]
__se_sys_access fs/open.c:550 [inline]
__x64_sys_access+0x5b/0x80 fs/open.c:550

do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:

ffff88802ad9b700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802ad9b780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802ad9b800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88802ad9b880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802ad9b900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit: 4b290aae Merge tag 'sysctl-6.17-rc1' of git://git.kern..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=120c8042580000

kernel config: https://syzkaller.appspot.com/x/.config?x=eb654b6c0c63cccc
dashboard link: https://syzkaller.appspot.com/bug?extid=0c815b25cdb3678e7083
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=16548042580000

[Sravan Kumar]

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 4b290aae788e06561754b28c6842e4080957d3f7

[Sravan Kumar]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 4b290aae788e06561754b28c6842e4080957d3f7

[Sravan Kumar]

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 4b290aae788e06561754b28c6842e4080957d3f7

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-out-of-bounds Read in fbcon_prepare_logo

==================================================================
BUG: KASAN: slab-out-of-bounds in scr_memcpyw include/linux/vt_buffer.h:38 [inline]
BUG: KASAN: slab-out-of-bounds in fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:618

Read of size 256 at addr ffff888144ebb860 by task syz.0.17/6639

CPU: 0 UID: 0 PID: 6639 Comm: syz.0.17 Not tainted 6.16.0-syzkaller-04405-g4b290aae788e #0 PREEMPT(full)

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xcd/0x630 mm/kasan/report.c:482
kasan_report+0xe0/0x110 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:189
__asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105
scr_memcpyw include/linux/vt_buffer.h:38 [inline]
fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:618

fbcon_init+0xd77/0x1900 drivers/video/fbdev/core/fbcon.c:1150
visual_init+0x31d/0x620 drivers/tty/vt/vt.c:1019

do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3915
vt_bind drivers/tty/vt/vt.c:4071 [inline]
store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4143

dev_attr_store+0x55/0x80 drivers/base/core.c:2437

sysfs_kf_write+0xef/0x150 fs/sysfs/file.c:145
kernfs_fop_write_iter+0x354/0x510 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x6c4/0x1150 fs/read_write.c:686
ksys_write+0x12a/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7f36be18e9a9

Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007f36bef23038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f36be3b5fa0 RCX: 00007f36be18e9a9

RDX: 0000000000000081 RSI: 00002000000001c0 RDI: 0000000000000004

RBP: 00007f36be210d69 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 0000000000000000 R14: 00007f36be3b5fa0 R15: 00007ffe05ac9a98
</TASK>

Allocated by task 1100:

kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:260 [inline]
__do_kmalloc_node mm/slub.c:4328 [inline]

__kmalloc_node_track_caller_noprof+0x221/0x510 mm/slub.c:4347
kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:601
__alloc_skb+0x166/0x380 net/core/skbuff.c:670
alloc_skb include/linux/skbuff.h:1336 [inline]
mld_newpack.isra.0+0x18e/0xa20 net/ipv6/mcast.c:1788
add_grhead+0x299/0x340 net/ipv6/mcast.c:1899
add_grec+0x112a/0x1680 net/ipv6/mcast.c:2037
mld_send_initial_cr.part.0+0xe2/0x260 net/ipv6/mcast.c:2282
mld_send_initial_cr include/linux/refcount.h:291 [inline]
ipv6_mc_dad_complete+0x22c/0x2b0 net/ipv6/mcast.c:2293
addrconf_dad_completed+0xd8a/0x10d0 net/ipv6/addrconf.c:4339
addrconf_dad_work+0x84d/0x14e0 net/ipv6/addrconf.c:4267

process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3321 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
kthread+0x3c2/0x780 kernel/kthread.c:464
ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 1100:

kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2381 [inline]
slab_free mm/slub.c:4643 [inline]
kfree+0x2b4/0x4d0 mm/slub.c:4842

skb_kfree_head net/core/skbuff.c:1048 [inline]
skb_free_head+0x114/0x210 net/core/skbuff.c:1060
skb_release_data+0x776/0x9c0 net/core/skbuff.c:1087
skb_release_all net/core/skbuff.c:1152 [inline]
__kfree_skb net/core/skbuff.c:1166 [inline]
sk_skb_reason_drop+0x129/0x1a0 net/core/skbuff.c:1204
kfree_skb_reason include/linux/skbuff.h:1275 [inline]
kfree_skb include/linux/skbuff.h:1284 [inline]
ip_tunnel_xmit+0x8e0/0x37b0 net/ipv4/ip_tunnel.c:869
__gre_xmit+0x8bb/0xc00 net/ipv4/ip_gre.c:488
gre_tap_xmit+0x3b3/0x630 net/ipv4/ip_gre.c:776
__netdev_start_xmit include/linux/netdevice.h:5215 [inline]
netdev_start_xmit include/linux/netdevice.h:5224 [inline]
xmit_one net/core/dev.c:3830 [inline]
dev_hard_start_xmit+0x97/0x740 net/core/dev.c:3846
sch_direct_xmit+0x1b2/0xcf0 net/sched/sch_generic.c:344
__dev_xmit_skb net/core/dev.c:4102 [inline]
__dev_queue_xmit+0x13c7/0x43e0 net/core/dev.c:4679
dev_queue_xmit include/linux/netdevice.h:3355 [inline]
neigh_hh_output include/net/neighbour.h:523 [inline]
neigh_output include/net/neighbour.h:537 [inline]
ip6_finish_output2+0xe98/0x2020 net/ipv6/ip6_output.c:141
__ip6_finish_output+0x3cd/0xff0 net/ipv6/ip6_output.c:215
ip6_finish_output net/ipv6/ip6_output.c:226 [inline]
NF_HOOK_COND include/linux/netfilter.h:306 [inline]
ip6_output+0x1f9/0x540 net/ipv6/ip6_output.c:247
dst_output include/net/dst.h:459 [inline]
NF_HOOK include/linux/netfilter.h:317 [inline]
NF_HOOK include/linux/netfilter.h:311 [inline]
mld_sendpack+0x9e9/0x1220 net/ipv6/mcast.c:1868
mld_send_initial_cr.part.0+0x1a1/0x260 net/ipv6/mcast.c:2285
mld_send_initial_cr include/linux/refcount.h:291 [inline]
ipv6_mc_dad_complete+0x22c/0x2b0 net/ipv6/mcast.c:2293
addrconf_dad_completed+0xd8a/0x10d0 net/ipv6/addrconf.c:4339
addrconf_dad_work+0x84d/0x14e0 net/ipv6/addrconf.c:4267

process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3321 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
kthread+0x3c2/0x780 kernel/kthread.c:464
ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888144ebb000

which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 96 bytes to the right of

allocated 2048-byte region [ffff888144ebb000, ffff888144ebb800)

The buggy address belongs to the physical page:

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x144eb8

head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0

anon flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88801b842000 0000000000000000 dead000000000001

raw: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000

head: 057ff00000000040 ffff88801b842000 0000000000000000 dead000000000001

head: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000

head: 057ff00000000003 ffffea000513ae01 00000000ffffffff 00000000ffffffff

head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 3818223817, free_ts 0

set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
prep_new_page mm/page_alloc.c:1712 [inline]
get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
__alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
alloc_slab_page mm/slub.c:2451 [inline]
allocate_slab mm/slub.c:2619 [inline]
new_slab+0x23b/0x330 mm/slub.c:2673
___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
__slab_alloc_node mm/slub.c:4024 [inline]
slab_alloc_node mm/slub.c:4185 [inline]

__kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4354
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
acpi_ds_create_walk_state+0x78/0x250 drivers/acpi/acpica/dswstate.c:518
acpi_ps_execute_method+0x253/0xb30 drivers/acpi/acpica/psxface.c:134
acpi_ns_evaluate+0x76c/0xca0 drivers/acpi/acpica/nseval.c:205
acpi_ut_evaluate_object+0xda/0x4a0 drivers/acpi/acpica/uteval.c:60
acpi_ut_execute_STA+0x87/0x1a0 drivers/acpi/acpica/uteval.c:223
acpi_ns_get_device_callback+0x23c/0x500 drivers/acpi/acpica/nsxfeval.c:723
acpi_ns_walk_namespace+0x405/0x5b0 drivers/acpi/acpica/nswalk.c:233
acpi_get_devices+0x137/0x160 drivers/acpi/acpica/nsxfeval.c:805
page_owner free stack trace missing

Memory state around the buggy address:

ffff888144ebb700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888144ebb780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888144ebb800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff888144ebb880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888144ebb900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

==================================================================


Tested on:

commit: 4b290aae Merge tag 'sysctl-6.17-rc1' of git://git.kern..

git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=10eb4042580000

kernel config: https://syzkaller.appspot.com/x/.config?x=eb654b6c0c63cccc
dashboard link: https://syzkaller.appspot.com/bug?extid=0c815b25cdb3678e7083
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.