syzbot


KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt

Status: upstream: reported C repro on 2026/01/14 12:28
Bug presence: origin:lts
[Documentation on labels]
Reported-by: syzbot+d9c81a0b02cc40bcc07c@syzkaller.appspotmail.com
First crash: 1d23h, last: 1d20h
Bug presence (2)
Date Name Commit Repro Result
2026/01/14 lts (merge base) 68efe5a6c16a C [report] KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt
2026/01/14 upstream (ToT) e0d4140e8043 C Didn't crash
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt bluetooth 17 C 36 640d 651d 0/29 auto-obsoleted due to no activity on 2024/06/24 18:09

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
BUG: KASAN: slab-out-of-bounds in copy_from_sockptr include/linux/sockptr.h:55 [inline]
BUG: KASAN: slab-out-of-bounds in l2cap_sock_setsockopt+0x1b8e/0x1f60 net/bluetooth/l2cap_sock.c:996
Read of size 4 at addr ffff88810dff3c0b by task syz.2.17/375

CPU: 1 PID: 375 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0xf1/0x140 mm/kasan/report.c:444
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report_generic.c:319
 copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
 copy_from_sockptr include/linux/sockptr.h:55 [inline]
 l2cap_sock_setsockopt+0x1b8e/0x1f60 net/bluetooth/l2cap_sock.c:996
 __sys_setsockopt+0x2f0/0x460 net/socket.c:2203
 __do_sys_setsockopt net/socket.c:2214 [inline]
 __se_sys_setsockopt net/socket.c:2211 [inline]
 __x64_sys_setsockopt+0xbf/0xd0 net/socket.c:2211
 x64_sys_call+0x982/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:55
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7efd173a3749
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:00007fff6ff46778 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007efd175f9fa0 RCX: 00007efd173a3749
RDX: 0000000000000008 RSI: 0000000000000112 RDI: 0000000000000004
RBP: 00007efd17427f91 R08: 0000000000000001 R09: 0000000000000000
R10: 0000200000000040 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efd175f9fa0 R14: 00007efd175f9fa0 R15: 0000000000000005
 </TASK>

Allocated by task 375:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:433 [inline]
 ____kasan_kmalloc mm/kasan/common.c:512 [inline]
 __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:521
 kasan_kmalloc include/linux/kasan.h:227 [inline]
 __kmalloc+0x13d/0x2c0 mm/slub.c:4436
 kmalloc include/linux/slab.h:624 [inline]
 __cgroup_bpf_run_filter_setsockopt+0x891/0xa40 kernel/bpf/cgroup.c:1511
 __sys_setsockopt+0x413/0x460 net/socket.c:2186
 __do_sys_setsockopt net/socket.c:2214 [inline]
 __se_sys_setsockopt net/socket.c:2211 [inline]
 __x64_sys_setsockopt+0xbf/0xd0 net/socket.c:2211
 x64_sys_call+0x982/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:55
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff88810dff3c08
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 3 bytes inside of
 8-byte region [ffff88810dff3c08, ffff88810dff3c10)
The buggy address belongs to the page:
page:ffffea000437fcc0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10dff3
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 0000000100000001 ffff888100042300
raw: 0000000000000000 0000000080660066 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 102, ts 4420357956, free_ts 0
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2611
 get_page_from_freelist+0x2cc5/0x2d50 mm/page_alloc.c:4485
 __alloc_pages+0x18f/0x440 mm/page_alloc.c:5808
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1937 [inline]
 new_slab+0xa1/0x4d0 mm/slub.c:2000
 ___slab_alloc+0x381/0x810 mm/slub.c:3033
 __slab_alloc+0x49/0x90 mm/slub.c:3120
 slab_alloc_node mm/slub.c:3211 [inline]
 slab_alloc mm/slub.c:3255 [inline]
 __kmalloc+0x16a/0x2c0 mm/slub.c:4432
 kmalloc include/linux/slab.h:624 [inline]
 kernfs_fop_write_iter+0x156/0x400 fs/kernfs/file.c:273
 call_write_iter include/linux/fs.h:2212 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x802/0xf70 fs/read_write.c:594
 ksys_write+0x140/0x240 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:656
 x64_sys_call+0x8ef/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88810dff3b00: fc fc fc fb fc fc fc fc fb fc fc fc fc fb fc fc
 ffff88810dff3b80: fc fc fb fc fc fc fc fb fc fc fc fc fb fc fc fc
>ffff88810dff3c00: fc 01 fc fc fc fc fb fc fc fc fc fb fc fc fc fc
                      ^
 ffff88810dff3c80: fb fc fc fc fc fb fc fc fc fc 00 fc fc fc fc fb
 ffff88810dff3d00: fc fc fc fc 00 fc fc fc fc fa fc fc fc fc fb fc
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/14 14:53 android13-5.15-lts 050dc55b0457 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt
2026/01/14 14:01 android13-5.15-lts 050dc55b0457 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt
2026/01/14 13:07 android13-5.15-lts 050dc55b0457 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt
2026/01/14 12:15 android13-5.15-lts 050dc55b0457 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt
2026/01/14 11:14 android13-5.15-lts 050dc55b0457 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt
* Struck through repros no longer work on HEAD.