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

Status: upstream: reported C repro on 2026/10/04 20:39
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+587fdbbd554e20a6e055@syzkaller.appspotmail.com
First crash: 3d17h, last: 2h28m
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/10/08 linux-5.15.y (ToT) a051a4bf909f C [report] KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/08 upstream (ToT) 0c2669a9f4a1 C Didn't crash
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: slab-out-of-bounds Read in sk_skb_adjust_room 17 syz, C 16 21h09m 3d21h 0/3 upstream: reported C repro on 2026/10/04 16:38
android-5-15 KASAN: slab-out-of-bounds Read in sk_skb_adjust_room 17 syz, C 6 1d05h 3d12h 0/2 upstream: reported C repro on 2026/10/05 01:06
android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room 19 syz, C 16 1d04h 3d12h 0/2 upstream: reported C repro on 2026/10/05 01:18

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in tls_get_ctx include/net/tls.h:493 [inline]
BUG: KASAN: slab-out-of-bounds in tls_sw_has_ctx_rx include/net/tls.h:601 [inline]
BUG: KASAN: slab-out-of-bounds in ____sk_skb_adjust_room net/core/filter.c:3673 [inline]
BUG: KASAN: slab-out-of-bounds in sk_skb_adjust_room+0x35e/0x590 net/core/filter.c:3650
Read of size 8 at addr ffff888025db4f80 by task syz.0.17/4326

CPU: 1 PID: 4326 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 tls_get_ctx include/net/tls.h:493 [inline]
 tls_sw_has_ctx_rx include/net/tls.h:601 [inline]
 ____sk_skb_adjust_room net/core/filter.c:3673 [inline]
 sk_skb_adjust_room+0x35e/0x590 net/core/filter.c:3650
 bpf_prog_e15ab8bd9cea3c06+0x19/0x1a4
 bpf_dispatcher_nop_func include/linux/bpf.h:890 [inline]
 __bpf_prog_run include/linux/filter.h:628 [inline]
 bpf_prog_run include/linux/filter.h:635 [inline]
 bpf_prog_run_pin_on_cpu include/linux/filter.h:652 [inline]
 sk_psock_verdict_recv+0x329/0x9a0 net/core/skmsg.c:1230
 unix_read_sock+0x10a/0x2d0 net/unix/af_unix.c:2432
 sk_psock_verdict_data_ready+0x167/0x1d0 net/core/skmsg.c:1253
 unix_stream_sendmsg+0x7d1/0xc90 net/unix/af_unix.c:2110
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 __sys_sendto+0x46d/0x620 net/socket.c:2073
 __do_sys_sendto net/socket.c:2085 [inline]
 __se_sys_sendto net/socket.c:2081 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:2081
 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: 0033:0x7f305bad8159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdde893298 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f305bd5ffa0 RCX: 00007f305bad8159
RDX: 0000000000000004 RSI: 0000200000000800 RDI: 0000000000000004
RBP: 00007f305bb6f06b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f305bd5ffac R14: 00007f305bd5ffa0 R15: 00007f305bd5ffa0
 </TASK>

Allocated by task 4326:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x92/0xc0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x15d/0x280 mm/slub.c:3238
 sk_prot_alloc+0x57/0x210 net/core/sock.c:1859
 sk_alloc+0x2f/0x310 net/core/sock.c:1921
 unix_create1+0xad/0x610 net/unix/af_unix.c:-1
 unix_create+0x139/0x1f0 net/unix/af_unix.c:929
 __sock_create+0x473/0x910 net/socket.c:1496
 sock_create net/socket.c:1552 [inline]
 __sys_socketpair+0x1bd/0x540 net/socket.c:1652
 __do_sys_socketpair net/socket.c:1705 [inline]
 __se_sys_socketpair net/socket.c:1702 [inline]
 __x64_sys_socketpair+0x97/0xb0 net/socket.c:1702
 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 ffff888025db4800
 which belongs to the cache UNIX-STREAM of size 1920
The buggy address is located 0 bytes to the right of
 1920-byte region [ffff888025db4800, ffff888025db4f80)
The buggy address belongs to the page:
page:ffffea0000976c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x25db0
head:ffffea0000976c00 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff888029e05401
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff8881467fd500
raw: 0000000000000000 0000000080100010 00000001ffffffff ffff888029e05401
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 4184, ts 61008081488, free_ts 59478763338
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x807/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0xf0/0x280 mm/slub.c:3238
 sk_prot_alloc+0x57/0x210 net/core/sock.c:1859
 sk_alloc+0x2f/0x310 net/core/sock.c:1921
 unix_create1+0xad/0x610 net/unix/af_unix.c:-1
 unix_stream_connect+0x308/0xf80 net/unix/af_unix.c:1352
 __sys_connect_file net/socket.c:1933 [inline]
 __sys_connect+0x3cb/0x450 net/socket.c:1950
 __do_sys_connect net/socket.c:1960 [inline]
 __se_sys_connect net/socket.c:1957 [inline]
 __x64_sys_connect+0x76/0x80 net/socket.c:1957
 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 last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 free_slab mm/slub.c:2020 [inline]
 discard_slab mm/slub.c:2026 [inline]
 __unfreeze_partials+0x188/0x1e0 mm/slub.c:2512
 put_cpu_partial+0x12d/0x190 mm/slub.c:2592
 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xc0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x15d/0x280 mm/slub.c:3238
 ptlock_alloc+0x1c/0x60 mm/memory.c:5556
 ptlock_init include/linux/mm.h:2241 [inline]
 pgtable_pte_page_ctor include/linux/mm.h:2268 [inline]
 __pte_alloc_one include/asm-generic/pgalloc.h:66 [inline]
 pte_alloc_one+0xc0/0x310 arch/x86/mm/pgtable.c:33
 __pte_alloc+0x21/0x150 mm/memory.c:439
 do_anonymous_page mm/memory.c:3806 [inline]
 handle_pte_fault mm/memory.c:4648 [inline]
 __handle_mm_fault mm/memory.c:4785 [inline]
 handle_mm_fault+0x39d9/0x4440 mm/memory.c:4883
 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355
 handle_page_fault arch/x86/mm/fault.c:1443 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606

Memory state around the buggy address:
 ffff888025db4e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888025db4f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888025db4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff888025db5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888025db5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/04 23:09 linux-5.15.y a051a4bf909f 57bbd979 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/04 22:17 linux-5.15.y a051a4bf909f 57bbd979 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/04 21:27 linux-5.15.y a051a4bf909f 57bbd979 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/07 17:59 linux-5.15.y a051a4bf909f 6520ecdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/07 17:58 linux-5.15.y a051a4bf909f 6520ecdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/07 09:10 linux-5.15.y a051a4bf909f f7710056 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/07 09:10 linux-5.15.y a051a4bf909f f7710056 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/05 08:01 linux-5.15.y a051a4bf909f 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/04 20:39 linux-5.15.y a051a4bf909f 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/04 20:38 linux-5.15.y a051a4bf909f 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
* Struck through repros no longer work on HEAD.