[moderation] [modules?] KASAN: slab-out-of-bounds Write in try_module_get (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8e621c9a3375 Merge tag 'net-6.18-rc7' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=110c9a12580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1cd7f786c0f5182f
dashboard link: https://syzkaller.appspot.com/bug?extid=71d5d861d9adc6905054
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [da.g...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org mcg...@kernel.org petr....@suse.com samito...@google.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6be75789d60e/disk-8e621c9a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/62e7a40cfe48/vmlinux-8e621c9a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3e523caa536d/bzImage-8e621c9a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+71d5d8...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: slab-out-of-bounds in atomic_inc_not_zero include/linux/atomic/atomic-instrumented.h:1536 [inline]
BUG: KASAN: slab-out-of-bounds in try_module_get+0x4c/0xd0 kernel/module/main.c:913
Write of size 4 at addr ffff888141a87f08 by task syz.1.7015/6511

CPU: 1 UID: 0 PID: 6511 Comm: syz.1.7015 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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:194 [inline]
kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:200
instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
atomic_inc_not_zero include/linux/atomic/atomic-instrumented.h:1536 [inline]
try_module_get+0x4c/0xd0 kernel/module/main.c:913
dvb_device_open+0x124/0x3b0 drivers/media/dvb-core/dvbdev.c:103
chrdev_open+0x234/0x6a0 fs/char_dev.c:414
do_dentry_open+0x982/0x1530 fs/open.c:965
vfs_open+0x82/0x3f0 fs/open.c:1097
do_open fs/namei.c:3975 [inline]
path_openat+0x1de4/0x2cb0 fs/namei.c:4134
do_filp_open+0x20b/0x470 fs/namei.c:4161
do_sys_openat2+0x11b/0x1d0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x174/0x210 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f14c238f749
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:00007f14c3243038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f14c25e5fa0 RCX: 00007f14c238f749
RDX: 0000000000000100 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007f14c2413f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f14c25e6038 R14: 00007f14c25e5fa0 R15: 00007fff9eaadb88
</TASK>

Allocated by task 1:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
kasan_save_track+0x14/0x30 mm/kasan/common.c:77
poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
dvb_register_device+0x1e4/0x2370 drivers/media/dvb-core/dvbdev.c:475
dvb_dmxdev_init+0x33e/0x4e0 drivers/media/dvb-core/dmxdev.c:1436
vidtv_bridge_dmxdev_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:343 [inline]
vidtv_bridge_dvb_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:445 [inline]
vidtv_bridge_probe+0x75d/0xa90 drivers/media/test-drivers/vidtv/vidtv_bridge.c:508
platform_probe+0x106/0x1d0 drivers/base/platform.c:1405
call_driver_probe drivers/base/dd.c:581 [inline]
really_probe+0x241/0xa90 drivers/base/dd.c:659
__driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
__driver_attach+0x283/0x580 drivers/base/dd.c:1217
bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:370
bus_add_driver+0x2e9/0x690 drivers/base/bus.c:678
driver_register+0x15c/0x4b0 drivers/base/driver.c:249
vidtv_bridge_init+0x45/0x80 drivers/media/test-drivers/vidtv/vidtv_bridge.c:598
do_one_initcall+0x123/0x6e0 init/main.c:1283
do_initcall_level init/main.c:1345 [inline]
do_initcalls init/main.c:1361 [inline]
do_basic_setup init/main.c:1380 [inline]
kernel_init_freeable+0x5c8/0x920 init/main.c:1593
kernel_init+0x1c/0x2b0 init/main.c:1483
ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888141a87e00
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 48 bytes to the right of
allocated 216-byte region [ffff888141a87e00, ffff888141a87ed8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x141a86
head: order:1 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 ffff88813ffa6b40 ffffea0001fdc480 0000000000000005
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88813ffa6b40 ffffea0001fdc480 0000000000000005
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000001 ffffea000506a181 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 19365672156, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1af/0x220 mm/page_alloc.c:1845
prep_new_page mm/page_alloc.c:1853 [inline]
get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3879
__alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5178
alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
alloc_slab_page mm/slub.c:3059 [inline]
allocate_slab mm/slub.c:3232 [inline]
new_slab+0x24a/0x360 mm/slub.c:3286
___slab_alloc+0xd79/0x1a50 mm/slub.c:4655
__slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4778
__slab_alloc_node mm/slub.c:4854 [inline]
slab_alloc_node mm/slub.c:5276 [inline]
__kmalloc_cache_noprof+0x477/0x780 mm/slub.c:5766
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
bus_add_driver+0x92/0x690 drivers/base/bus.c:662
driver_register+0x15c/0x4b0 drivers/base/driver.c:249
usb_register_driver+0x216/0x4d0 drivers/usb/core/driver.c:1078
do_one_initcall+0x123/0x6e0 init/main.c:1283
do_initcall_level init/main.c:1345 [inline]
do_initcalls init/main.c:1361 [inline]
do_basic_setup init/main.c:1380 [inline]
kernel_init_freeable+0x5c8/0x920 init/main.c:1593
kernel_init+0x1c/0x2b0 init/main.c:1483
ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page_owner free stack trace missing

Memory state around the buggy address:
ffff888141a87e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888141a87e80: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
>ffff888141a87f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff888141a87f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888141a88000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


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