KASAN: use-after-free Read in sk_skb_adjust_room

Status: upstream: reported C repro on 2026/10/05 01:18
Reported-by: syzbot+1067a8216997e9350068@syzkaller.appspotmail.com
First crash: 4d02h, last: 1d17h
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 KASAN: slab-out-of-bounds Read in sk_skb_adjust_room origin:lts-only 17 syz, C 10 15h32m 4d06h 0/3 upstream: reported C repro on 2026/10/04 20:39
linux-6.1 KASAN: slab-out-of-bounds Read in sk_skb_adjust_room 17 syz, C 16 1d10h 4d10h 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 1d18h 4d01h 0/2 upstream: reported C repro on 2026/10/05 01:06

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in tls_get_ctx include/net/tls.h:395 [inline]
BUG: KASAN: use-after-free in tls_sw_has_ctx_rx include/net/tls.h:427 [inline]
BUG: KASAN: use-after-free in ____sk_skb_adjust_room net/core/filter.c:3684 [inline]
BUG: KASAN: use-after-free in sk_skb_adjust_room+0x34e/0x610 net/core/filter.c:3661
Read of size 8 at addr ffff88810ff5a348 by task syz-executor286/312

CPU: 0 PID: 312 Comm: syz-executor286 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351
 tls_get_ctx include/net/tls.h:395 [inline]
 tls_sw_has_ctx_rx include/net/tls.h:427 [inline]
 ____sk_skb_adjust_room net/core/filter.c:3684 [inline]
 sk_skb_adjust_room+0x34e/0x610 net/core/filter.c:3661
 bpf_prog_e15ab8bd9cea3c06+0x19/0x20
 bpf_dispatcher_nop_func include/linux/bpf.h:987 [inline]
 __bpf_prog_run include/linux/filter.h:607 [inline]
 bpf_prog_run include/linux/filter.h:614 [inline]
 bpf_prog_run_pin_on_cpu include/linux/filter.h:631 [inline]
 sk_psock_verdict_recv+0x1c8/0x7b0 net/core/skmsg.c:1250
 unix_stream_read_skb+0x12e/0x2f0 net/unix/af_unix.c:2754
 sk_psock_verdict_data_ready+0xaf/0x1d0 net/core/skmsg.c:1268
 unix_stream_sendmsg+0x631/0xa80 net/unix/af_unix.c:2250
 sock_sendmsg_nosec net/socket.c:716 [inline]
 __sock_sendmsg net/socket.c:728 [inline]
 __sys_sendto+0x4ac/0x660 net/socket.c:2143
 __do_sys_sendto net/socket.c:2155 [inline]
 __se_sys_sendto net/socket.c:2151 [inline]
 __x64_sys_sendto+0xe5/0x100 net/socket.c:2151
 x64_sys_call+0x83/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f34dd171509
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f34dd145208 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f34dd21cb88 RCX: 00007f34dd171509
RDX: 0000000000000001 RSI: 0000200000000800 RDI: 0000000000000004
RBP: 00007f34dd21cb80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f34dd1e8bcc
R13: 0000200000000600 R14: 0000200000000608 R15: 0000200000000800
 </TASK>

Allocated by task 299:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
 __kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:334
 kasan_slab_alloc include/linux/kasan.h:202 [inline]
 slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
 slab_alloc_node mm/slub.c:3382 [inline]
 slab_alloc mm/slub.c:3392 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3399 [inline]
 kmem_cache_alloc+0x166/0x320 mm/slub.c:3408
 sk_prot_alloc+0x5f/0x320 net/core/sock.c:2053
 sk_alloc+0x3b/0x460 net/core/sock.c:2119
 unix_create1+0xb8/0x710 net/unix/af_unix.c:-1
 unix_create+0x149/0x200 net/unix/af_unix.c:1019
 __sock_create+0x39e/0x7c0 net/socket.c:1540
 sock_create net/socket.c:1596 [inline]
 __sys_socket_create net/socket.c:1633 [inline]
 __sys_socket+0xcd/0x1a0 net/socket.c:1661
 __do_sys_socket net/socket.c:1674 [inline]
 __se_sys_socket net/socket.c:1672 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1672
 x64_sys_call+0x449/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:42
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 299:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
 kasan_slab_free include/linux/kasan.h:178 [inline]
 slab_free_hook mm/slub.c:1750 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
 slab_free mm/slub.c:3712 [inline]
 kmem_cache_free+0x12d/0x300 mm/slub.c:3737
 sk_prot_free net/core/sock.c:2100 [inline]
 __sk_destruct+0x4b4/0x5e0 net/core/sock.c:2188
 sk_destruct net/core/sock.c:2203 [inline]
 __sk_free+0x30a/0x400 net/core/sock.c:2214
 sk_free+0x54/0x90 net/core/sock.c:2225
 sock_put include/net/sock.h:2099 [inline]
 unix_release_sock+0xb6d/0xe60 net/unix/af_unix.c:654
 unix_release+0x9d/0xd0 net/unix/af_unix.c:1034
 __sock_release net/socket.c:652 [inline]
 sock_close+0xc9/0x220 net/socket.c:1390
 __fput+0x1fd/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x9b/0xb0 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88810ff5a300
 which belongs to the cache UNIX-STREAM of size 1152
The buggy address is located 72 bytes inside of
 1152-byte region [ffff88810ff5a300, ffff88810ff5a780)

The buggy address belongs to the physical page:
page:ffffea00043fd600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10ff58
head:ffffea00043fd600 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000001 ffff888108c73800
raw: 0000000000000000 00000000800c000c 00000001ffffffff 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 87, tgid 87 (acpid), ts 8701575750, free_ts 0
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2673
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2680
 get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4587
 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5931
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3e0 mm/slub.c:2020
 ___slab_alloc+0x70f/0xb70 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 slab_alloc mm/slub.c:3392 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3399 [inline]
 kmem_cache_alloc+0x1a8/0x320 mm/slub.c:3408
 sk_prot_alloc+0x5f/0x320 net/core/sock.c:2053
 sk_alloc+0x3b/0x460 net/core/sock.c:2119
 unix_create1+0xb8/0x710 net/unix/af_unix.c:-1
 unix_create+0x149/0x200 net/unix/af_unix.c:1019
 __sock_create+0x39e/0x7c0 net/socket.c:1540
 sock_create net/socket.c:1596 [inline]
 __sys_socket_create net/socket.c:1633 [inline]
 __sys_socket+0xcd/0x1a0 net/socket.c:1661
 __do_sys_socket net/socket.c:1674 [inline]
 __se_sys_socket net/socket.c:1672 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1672
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88810ff5a200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88810ff5a280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88810ff5a300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff88810ff5a380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810ff5a400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (16):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/05 01:40 android14-6.1 6612ef9d0b09 57bbd979 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/05 01:15 android14-6.1 6612ef9d0b09 57bbd979 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/05 02:02 android14-6.1 6612ef9d0b09 57bbd979 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/05 01:19 android14-6.1 6612ef9d0b09 57bbd979 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/07 09:02 android14-6.1 3b0884642a50 f7710056 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/07 07:38 android14-6.1 3b0884642a50 f7710056 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/07 07:37 android14-6.1 3b0884642a50 f7710056 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/07 07:37 android14-6.1 3b0884642a50 f7710056 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/05 12:21 android14-6.1 6612ef9d0b09 af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/05 12:21 android14-6.1 6612ef9d0b09 af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/05 12:20 android14-6.1 6612ef9d0b09 af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/05 12:20 android14-6.1 6612ef9d0b09 af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/05 00:44 android14-6.1 6612ef9d0b09 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/05 00:44 android14-6.1 6612ef9d0b09 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in sk_skb_adjust_room
2026/10/05 12:21 android14-6.1 6612ef9d0b09 af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
2026/10/05 00:44 android14-6.1 6612ef9d0b09 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: slab-out-of-bounds Read in sk_skb_adjust_room
* Struck through repros no longer work on HEAD.