Hello,
syzbot found the following issue on:
HEAD commit: 1e89a1be4fe9 Linux 6.6.117
git tree: linux-6.6.y
console output:
https://syzkaller.appspot.com/x/log.txt?x=17d82612580000
kernel config:
https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link:
https://syzkaller.appspot.com/bug?extid=ed23eef9ae764b5860ad
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image:
https://storage.googleapis.com/syzbot-assets/ad3647e47b66/disk-1e89a1be.raw.xz
vmlinux:
https://storage.googleapis.com/syzbot-assets/d6f7ba94aea7/vmlinux-1e89a1be.xz
kernel image:
https://storage.googleapis.com/syzbot-assets/e08af2290355/bzImage-1e89a1be.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by:
syzbot+ed23ee...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in skb_dst_drop include/net/dst.h:281 [inline]
BUG: KASAN: slab-use-after-free in skb_release_head_state+0x3b/0x240 net/core/skbuff.c:1040
Read of size 8 at addr ffff88802d9e2698 by task syz.1.20965/20740
CPU: 1 PID: 20740 Comm: syz.1.20965 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xac/0x220 mm/kasan/report.c:468
kasan_report+0x117/0x150 mm/kasan/report.c:581
skb_dst_drop include/net/dst.h:281 [inline]
skb_release_head_state+0x3b/0x240 net/core/skbuff.c:1040
skb_release_all net/core/skbuff.c:1055 [inline]
__kfree_skb net/core/skbuff.c:1071 [inline]
kfree_skb_reason+0xd7/0x170 net/core/skbuff.c:1107
kfree_skb include/linux/skbuff.h:1232 [inline]
__hci_req_sync+0x629/0x900 net/bluetooth/hci_request.c:184
hci_req_sync+0xa2/0xc0 net/bluetooth/hci_request.c:206
hci_inquiry+0x38e/0x600 net/bluetooth/hci_core.c:394
sock_do_ioctl+0xd7/0x2f0 net/socket.c:1222
sock_ioctl+0x623/0x7a0 net/socket.c:1341
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa1a2f8f749
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:00007fa1a3e73038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa1a31e5fa0 RCX: 00007fa1a2f8f749
RDX: 0000200000000140 RSI: 00000000800448f0 RDI: 0000000000000004
RBP: 00007fa1a3013f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa1a31e6038 R14: 00007fa1a31e5fa0 R15: 00007ffe20e9b3c8
</TASK>
Allocated by task 27436:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:328
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
slab_alloc mm/slub.c:3503 [inline]
__kmem_cache_alloc_lru mm/slub.c:3510 [inline]
kmem_cache_alloc+0x11e/0x2e0 mm/slub.c:3519
skb_clone+0x1eb/0x370 net/core/skbuff.c:1915
hci_send_cmd_sync net/bluetooth/hci_core.c:4067 [inline]
hci_cmd_work+0x283/0x660 net/bluetooth/hci_core.c:4087
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
Freed by task 51:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1811 [inline]
slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1837
slab_free mm/slub.c:3830 [inline]
kmem_cache_free+0xf8/0x280 mm/slub.c:3852
kfree_skb include/linux/skbuff.h:1232 [inline]
hci_send_cmd_sync net/bluetooth/hci_core.c:4066 [inline]
hci_cmd_work+0x25d/0x660 net/bluetooth/hci_core.c:4087
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
The buggy address belongs to the object at ffff88802d9e2640
which belongs to the cache skbuff_head_cache of size 240
The buggy address is located 88 bytes inside of
freed 240-byte region [ffff88802d9e2640, ffff88802d9e2730)
The buggy address belongs to the physical page:
page:ffffea0000b67880 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2d9e2
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888143242640 ffffea000105a040 dead000000000004
raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 5800, tgid 5800 (udevd), ts 85993113591, free_ts 83872643342
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
alloc_slab_page+0x5d/0x170 mm/slub.c:1881
allocate_slab mm/slub.c:2028 [inline]
new_slab+0x87/0x2e0 mm/slub.c:2081
___slab_alloc+0xc6d/0x1300 mm/slub.c:3253
__slab_alloc mm/slub.c:3339 [inline]
__slab_alloc_node mm/slub.c:3392 [inline]
slab_alloc_node mm/slub.c:3485 [inline]
kmem_cache_alloc_node+0x1ea/0x330 mm/slub.c:3540
__alloc_skb+0x108/0x2c0 net/core/skbuff.c:643
alloc_skb include/linux/skbuff.h:1284 [inline]
alloc_skb_with_frags+0xca/0x7c0 net/core/skbuff.c:6332
sock_alloc_send_pskb+0x857/0x990 net/core/sock.c:2821
unix_dgram_sendmsg+0x5a1/0x1720 net/unix/af_unix.c:2001
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
sock_write_iter+0x2bb/0x3f0 net/socket.c:1160
call_write_iter include/linux/fs.h:2018 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x43b/0x940 fs/read_write.c:584
ksys_write+0x147/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2127 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
put_cpu_partial+0x17c/0x250 mm/slub.c:2743
__slab_free+0x31d/0x410 mm/slub.c:3700
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
__kmem_cache_alloc_node+0x13e/0x260 mm/slub.c:3534
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0xa4/0x240 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x1c3/0x3c0 security/tomoyo/file.c:771
security_file_open+0x62/0xa0 security/security.c:2854
do_dentry_open+0x380/0x1500 fs/open.c:916
do_open fs/namei.c:3640 [inline]
path_openat+0x274b/0x3190 fs/namei.c:3797
Memory state around the buggy address:
ffff88802d9e2580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
ffff88802d9e2600: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff88802d9e2680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802d9e2700: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
ffff88802d9e2780: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
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