[v5.15] KASAN: slab-out-of-bounds Read in __xfrm_decode_session (3)
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syzbot
Apr 11, 2026, 5:07:33 PM (4 days ago) Apr 11
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 91d48252ad4b Linux 5.15.202
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17ca9106580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=45602763b68b48e65f94
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/74e75dfcb812/disk-91d48252.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bfa72aab00f2/vmlinux-91d48252.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47ea72d1c7dc/bzImage-91d48252.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+456027...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-out-of-bounds in decode_session6 net/xfrm/xfrm_policy.c:3413 [inline]
BUG: KASAN: slab-out-of-bounds in __xfrm_decode_session+0x17ae/0x1fa0 net/xfrm/xfrm_policy.c:3520
Read of size 1 at addr ffff88807c7f1bd6 by task syz.1.396/6164
CPU: 0 PID: 6164 Comm: syz.1.396 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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
decode_session6 net/xfrm/xfrm_policy.c:3413 [inline]
__xfrm_decode_session+0x17ae/0x1fa0 net/xfrm/xfrm_policy.c:3520
xfrm_decode_session_reverse include/net/xfrm.h:1170 [inline]
icmpv6_route_lookup+0x3ea/0x5a0 net/ipv6/icmp.c:394
icmp6_send+0xff2/0x1990 net/ipv6/icmp.c:601
__icmpv6_send include/linux/icmpv6.h:28 [inline]
icmpv6_send include/linux/icmpv6.h:49 [inline]
ip6_link_failure+0x35/0x490 net/ipv6/route.c:2788
dst_link_failure include/net/dst.h:422 [inline]
ip6_tnl_xmit+0x671/0x23e0 net/ipv6/ip6_tunnel.c:1274
ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1390 [inline]
ip6_tnl_start_xmit+0xd27/0x12d0 net/ipv6/ip6_tunnel.c:1439
__netdev_start_xmit include/linux/netdevice.h:5036 [inline]
netdev_start_xmit include/linux/netdevice.h:5050 [inline]
xmit_one net/core/dev.c:3662 [inline]
dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3678
sch_direct_xmit+0x25a/0x4b0 net/sched/sch_generic.c:345
qdisc_restart net/sched/sch_generic.c:410 [inline]
__qdisc_run+0xa7e/0x1490 net/sched/sch_generic.c:418
__dev_xmit_skb net/core/dev.c:3955 [inline]
__dev_queue_xmit+0xe3d/0x2f80 net/core/dev.c:4266
neigh_output include/net/neighbour.h:509 [inline]
ip6_finish_output2+0x108c/0x1510 net/ipv6/ip6_output.c:130
ip6_fragment+0x133d/0x1ee0 net/ipv6/ip6_output.c:998
dst_output include/net/dst.h:452 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ip6_xmit+0x109b/0x16d0 net/ipv6/ip6_output.c:338
sctp_v6_xmit+0x985/0x11b0 net/sctp/ipv6.c:250
sctp_packet_transmit+0x239c/0x2910 net/sctp/output.c:652
sctp_packet_singleton+0x231/0x330 net/sctp/outqueue.c:780
sctp_outq_flush_ctrl net/sctp/outqueue.c:911 [inline]
sctp_outq_flush+0x4ac/0x3100 net/sctp/outqueue.c:1209
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:-1 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline]
sctp_do_sm+0x4ee2/0x55f0 net/sctp/sm_sideeffect.c:1170
sctp_primitive_ASSOCIATE+0x91/0xc0 net/sctp/primitive.c:73
sctp_sendmsg_to_asoc+0x14a7/0x1d90 net/sctp/socket.c:1840
sctp_sendmsg+0x196a/0x2900 net/sctp/socket.c:2030
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
__sys_sendmmsg+0x2ba/0x500 net/socket.c:2585
__do_sys_sendmmsg net/socket.c:2614 [inline]
__se_sys_sendmmsg net/socket.c:2611 [inline]
__x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2611
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: 0033:0x7fe246fd6819
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:00007fe24520f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fe247250090 RCX: 00007fe246fd6819
RDX: 0000000000000002 RSI: 0000200000002fc0 RDI: 0000000000000005
RBP: 00007fe24706cc91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000024000045 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe247250128 R14: 00007fe247250090 R15: 00007ffd4358a2e8
</TASK>
Allocated by task 5708:
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_kmalloc mm/kasan/common.c:513 [inline]
__kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
kmalloc include/linux/slab.h:607 [inline]
kzalloc include/linux/slab.h:738 [inline]
kernfs_iop_get_link+0x63/0x540 fs/kernfs/symlink.c:135
vfs_readlink+0x179/0x3e0 fs/namei.c:5089
do_readlinkat+0x251/0x490 fs/stat.c:454
__do_sys_readlink fs/stat.c:475 [inline]
__se_sys_readlink fs/stat.c:472 [inline]
__x64_sys_readlink+0x7b/0x90 fs/stat.c:472
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
Freed by task 5708:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1710 [inline]
slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
slab_free mm/slub.c:3504 [inline]
kfree+0xef/0x2a0 mm/slub.c:4564
do_delayed_call include/linux/delayed_call.h:28 [inline]
vfs_readlink+0x22a/0x3e0 fs/namei.c:5094
do_readlinkat+0x251/0x490 fs/stat.c:454
__do_sys_readlink fs/stat.c:475 [inline]
__se_sys_readlink fs/stat.c:472 [inline]
__x64_sys_readlink+0x7b/0x90 fs/stat.c:472
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 ffff88807c7f0000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 3030 bytes to the right of
4096-byte region [ffff88807c7f0000, ffff88807c7f1000)
The buggy address belongs to the page:
page:ffffea0001f1fc00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7c7f0
head:ffffea0001f1fc00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888016c42140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4295, ts 121029600140, free_ts 120895737515
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x1bbd/0x1ca0 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+0x80a/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]
__kmalloc+0x1cd/0x330 mm/slub.c:4408
kmalloc include/linux/slab.h:612 [inline]
tomoyo_realpath_from_path+0x118/0x610 security/tomoyo/realpath.c:254
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x23f/0x5d0 security/tomoyo/file.c:822
security_inode_getattr+0xcf/0x120 security/security.c:1348
vfs_getattr+0x26/0x3a0 fs/stat.c:157
vfs_statx+0x14e/0x500 fs/stat.c:225
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat fs/stat.c:411 [inline]
__se_sys_newfstatat fs/stat.c:405 [inline]
__x64_sys_newfstatat+0x15f/0x200 fs/stat.c:405
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+0x1a5/0x200 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/0xd0 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+0x100/0x290 mm/slub.c:3238
getname_flags+0xb5/0x500 fs/namei.c:138
user_path_at_empty+0x2a/0x190 fs/namei.c:2890
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0x107/0x500 fs/stat.c:221
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat fs/stat.c:411 [inline]
__se_sys_newfstatat fs/stat.c:405 [inline]
__x64_sys_newfstatat+0x15f/0x200 fs/stat.c:405
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
Memory state around the buggy address:
ffff88807c7f1a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88807c7f1b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88807c7f1b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88807c7f1c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88807c7f1c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 91d48252ad4b Linux 5.15.202
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17ca9106580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=45602763b68b48e65f94
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/74e75dfcb812/disk-91d48252.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bfa72aab00f2/vmlinux-91d48252.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47ea72d1c7dc/bzImage-91d48252.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+456027...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-out-of-bounds in decode_session6 net/xfrm/xfrm_policy.c:3413 [inline]
BUG: KASAN: slab-out-of-bounds in __xfrm_decode_session+0x17ae/0x1fa0 net/xfrm/xfrm_policy.c:3520
Read of size 1 at addr ffff88807c7f1bd6 by task syz.1.396/6164
CPU: 0 PID: 6164 Comm: syz.1.396 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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
decode_session6 net/xfrm/xfrm_policy.c:3413 [inline]
__xfrm_decode_session+0x17ae/0x1fa0 net/xfrm/xfrm_policy.c:3520
xfrm_decode_session_reverse include/net/xfrm.h:1170 [inline]
icmpv6_route_lookup+0x3ea/0x5a0 net/ipv6/icmp.c:394
icmp6_send+0xff2/0x1990 net/ipv6/icmp.c:601
__icmpv6_send include/linux/icmpv6.h:28 [inline]
icmpv6_send include/linux/icmpv6.h:49 [inline]
ip6_link_failure+0x35/0x490 net/ipv6/route.c:2788
dst_link_failure include/net/dst.h:422 [inline]
ip6_tnl_xmit+0x671/0x23e0 net/ipv6/ip6_tunnel.c:1274
ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1390 [inline]
ip6_tnl_start_xmit+0xd27/0x12d0 net/ipv6/ip6_tunnel.c:1439
__netdev_start_xmit include/linux/netdevice.h:5036 [inline]
netdev_start_xmit include/linux/netdevice.h:5050 [inline]
xmit_one net/core/dev.c:3662 [inline]
dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3678
sch_direct_xmit+0x25a/0x4b0 net/sched/sch_generic.c:345
qdisc_restart net/sched/sch_generic.c:410 [inline]
__qdisc_run+0xa7e/0x1490 net/sched/sch_generic.c:418
__dev_xmit_skb net/core/dev.c:3955 [inline]
__dev_queue_xmit+0xe3d/0x2f80 net/core/dev.c:4266
neigh_output include/net/neighbour.h:509 [inline]
ip6_finish_output2+0x108c/0x1510 net/ipv6/ip6_output.c:130
ip6_fragment+0x133d/0x1ee0 net/ipv6/ip6_output.c:998
dst_output include/net/dst.h:452 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ip6_xmit+0x109b/0x16d0 net/ipv6/ip6_output.c:338
sctp_v6_xmit+0x985/0x11b0 net/sctp/ipv6.c:250
sctp_packet_transmit+0x239c/0x2910 net/sctp/output.c:652
sctp_packet_singleton+0x231/0x330 net/sctp/outqueue.c:780
sctp_outq_flush_ctrl net/sctp/outqueue.c:911 [inline]
sctp_outq_flush+0x4ac/0x3100 net/sctp/outqueue.c:1209
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:-1 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline]
sctp_do_sm+0x4ee2/0x55f0 net/sctp/sm_sideeffect.c:1170
sctp_primitive_ASSOCIATE+0x91/0xc0 net/sctp/primitive.c:73
sctp_sendmsg_to_asoc+0x14a7/0x1d90 net/sctp/socket.c:1840
sctp_sendmsg+0x196a/0x2900 net/sctp/socket.c:2030
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
__sys_sendmmsg+0x2ba/0x500 net/socket.c:2585
__do_sys_sendmmsg net/socket.c:2614 [inline]
__se_sys_sendmmsg net/socket.c:2611 [inline]
__x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2611
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: 0033:0x7fe246fd6819
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:00007fe24520f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fe247250090 RCX: 00007fe246fd6819
RDX: 0000000000000002 RSI: 0000200000002fc0 RDI: 0000000000000005
RBP: 00007fe24706cc91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000024000045 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe247250128 R14: 00007fe247250090 R15: 00007ffd4358a2e8
</TASK>
Allocated by task 5708:
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_kmalloc mm/kasan/common.c:513 [inline]
__kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
kmalloc include/linux/slab.h:607 [inline]
kzalloc include/linux/slab.h:738 [inline]
kernfs_iop_get_link+0x63/0x540 fs/kernfs/symlink.c:135
vfs_readlink+0x179/0x3e0 fs/namei.c:5089
do_readlinkat+0x251/0x490 fs/stat.c:454
__do_sys_readlink fs/stat.c:475 [inline]
__se_sys_readlink fs/stat.c:472 [inline]
__x64_sys_readlink+0x7b/0x90 fs/stat.c:472
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
Freed by task 5708:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1710 [inline]
slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
slab_free mm/slub.c:3504 [inline]
kfree+0xef/0x2a0 mm/slub.c:4564
do_delayed_call include/linux/delayed_call.h:28 [inline]
vfs_readlink+0x22a/0x3e0 fs/namei.c:5094
do_readlinkat+0x251/0x490 fs/stat.c:454
__do_sys_readlink fs/stat.c:475 [inline]
__se_sys_readlink fs/stat.c:472 [inline]
__x64_sys_readlink+0x7b/0x90 fs/stat.c:472
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 ffff88807c7f0000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 3030 bytes to the right of
4096-byte region [ffff88807c7f0000, ffff88807c7f1000)
The buggy address belongs to the page:
page:ffffea0001f1fc00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7c7f0
head:ffffea0001f1fc00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888016c42140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4295, ts 121029600140, free_ts 120895737515
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x1bbd/0x1ca0 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+0x80a/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]
__kmalloc+0x1cd/0x330 mm/slub.c:4408
kmalloc include/linux/slab.h:612 [inline]
tomoyo_realpath_from_path+0x118/0x610 security/tomoyo/realpath.c:254
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x23f/0x5d0 security/tomoyo/file.c:822
security_inode_getattr+0xcf/0x120 security/security.c:1348
vfs_getattr+0x26/0x3a0 fs/stat.c:157
vfs_statx+0x14e/0x500 fs/stat.c:225
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat fs/stat.c:411 [inline]
__se_sys_newfstatat fs/stat.c:405 [inline]
__x64_sys_newfstatat+0x15f/0x200 fs/stat.c:405
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+0x1a5/0x200 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/0xd0 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+0x100/0x290 mm/slub.c:3238
getname_flags+0xb5/0x500 fs/namei.c:138
user_path_at_empty+0x2a/0x190 fs/namei.c:2890
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0x107/0x500 fs/stat.c:221
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat fs/stat.c:411 [inline]
__se_sys_newfstatat fs/stat.c:405 [inline]
__x64_sys_newfstatat+0x15f/0x200 fs/stat.c:405
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
Memory state around the buggy address:
ffff88807c7f1a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88807c7f1b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88807c7f1b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88807c7f1c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88807c7f1c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot
Apr 11, 2026, 7:28:29 PM (4 days ago) Apr 11
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:
HEAD commit: 91d48252ad4b Linux 5.15.202
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1077c0ce580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=166e07d6580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/74e75dfcb812/disk-91d48252.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bfa72aab00f2/vmlinux-91d48252.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47ea72d1c7dc/bzImage-91d48252.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+456027...@syzkaller.appspotmail.com
netlink: 80 bytes leftover after parsing attributes in process `syz.0.18'.
CPU: 1 PID: 4307 Comm: syz.0.18 Not tainted syzkaller #0
RIP: 0033:0x7fdb77c08819
RAX: ffffffffffffffda RBX: 00007fdb77e81fa0 RCX: 00007fdb77c08819
RDX: 0000000000000002 RSI: 0000200000002fc0 RDI: 0000000000000004
RBP: 00007fdb77c9ec91 R08: 0000000000000000 R09: 0000000000000000
</TASK>
Allocated by task 0:
(stack is not available)
The buggy address belongs to the object at ffff8880759bb000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 718 bytes inside of
2048-byte region [ffff8880759bb000, ffff8880759bb800)
head:ffffea0001d66e00 order:3 compound_mapcount:0 compound_pincount:0
raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000
kmalloc_reserve net/core/skbuff.c:356 [inline]
__alloc_skb+0x22c/0x750 net/core/skbuff.c:427
alloc_skb include/linux/skbuff.h:1162 [inline]
ip6_frag_next+0x128/0xbb0 net/ipv6/ip6_output.c:777
ip6_fragment+0x12ee/0x1ee0 net/ipv6/ip6_output.c:988
ffff8880759bb200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880759bb280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff8880759bb300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880759bb380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
HEAD commit: 91d48252ad4b Linux 5.15.202
git tree: linux-5.15.y
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=45602763b68b48e65f94
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1477c0ce580000
dashboard link: https://syzkaller.appspot.com/bug?extid=45602763b68b48e65f94
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=166e07d6580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/74e75dfcb812/disk-91d48252.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bfa72aab00f2/vmlinux-91d48252.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47ea72d1c7dc/bzImage-91d48252.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+456027...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-out-of-bounds in decode_session6 net/xfrm/xfrm_policy.c:3413 [inline]
BUG: KASAN: slab-out-of-bounds in __xfrm_decode_session+0x17ae/0x1fa0 net/xfrm/xfrm_policy.c:3520
Read of size 1 at addr ffff8880759bb2ce by task syz.0.18/4307
BUG: KASAN: slab-out-of-bounds in decode_session6 net/xfrm/xfrm_policy.c:3413 [inline]
BUG: KASAN: slab-out-of-bounds in __xfrm_decode_session+0x17ae/0x1fa0 net/xfrm/xfrm_policy.c:3520
CPU: 1 PID: 4307 Comm: syz.0.18 Not tainted syzkaller #0
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:00007ffdf5e8ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fdb77e81fa0 RCX: 00007fdb77c08819
RDX: 0000000000000002 RSI: 0000200000002fc0 RDI: 0000000000000004
RBP: 00007fdb77c9ec91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000024000045 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdb77e81fac R14: 00007fdb77e81fa0 R15: 00007fdb77e81fa0
</TASK>
Allocated by task 0:
(stack is not available)
The buggy address belongs to the object at ffff8880759bb000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 718 bytes inside of
2048-byte region [ffff8880759bb000, ffff8880759bb800)
The buggy address belongs to the page:
page:ffffea0001d66e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x759b8
head:ffffea0001d66e00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888016c42000
raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4307, ts 74437988897, free_ts 74405289260
page_owner tracks the page as allocated
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x1bbd/0x1ca0 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+0x80a/0xdd0 mm/slub.c:3013
__slab_alloc mm/slub.c:3100 [inline]
slab_alloc_node mm/slub.c:3191 [inline]
__kmalloc_node_track_caller+0x1fc/0x3a0 mm/slub.c:4963
get_page_from_freelist+0x1bbd/0x1ca0 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+0x80a/0xdd0 mm/slub.c:3013
__slab_alloc mm/slub.c:3100 [inline]
slab_alloc_node mm/slub.c:3191 [inline]
kmalloc_reserve net/core/skbuff.c:356 [inline]
__alloc_skb+0x22c/0x750 net/core/skbuff.c:427
alloc_skb include/linux/skbuff.h:1162 [inline]
ip6_frag_next+0x128/0xbb0 net/ipv6/ip6_output.c:777
ip6_fragment+0x12ee/0x1ee0 net/ipv6/ip6_output.c:988
dst_output include/net/dst.h:452 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ip6_xmit+0x109b/0x16d0 net/ipv6/ip6_output.c:338
sctp_v6_xmit+0x985/0x11b0 net/sctp/ipv6.c:250
sctp_packet_transmit+0x239c/0x2910 net/sctp/output.c:652
sctp_packet_singleton+0x231/0x330 net/sctp/outqueue.c:780
sctp_outq_flush_ctrl net/sctp/outqueue.c:911 [inline]
sctp_outq_flush+0x4ac/0x3100 net/sctp/outqueue.c:1209
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:-1 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline]
sctp_do_sm+0x4ee2/0x55f0 net/sctp/sm_sideeffect.c:1170
sctp_primitive_ASSOCIATE+0x91/0xc0 net/sctp/primitive.c:73
sctp_sendmsg_to_asoc+0x14a7/0x1d90 net/sctp/socket.c:1840
NF_HOOK include/linux/netfilter.h:302 [inline]
ip6_xmit+0x109b/0x16d0 net/ipv6/ip6_output.c:338
sctp_v6_xmit+0x985/0x11b0 net/sctp/ipv6.c:250
sctp_packet_transmit+0x239c/0x2910 net/sctp/output.c:652
sctp_packet_singleton+0x231/0x330 net/sctp/outqueue.c:780
sctp_outq_flush_ctrl net/sctp/outqueue.c:911 [inline]
sctp_outq_flush+0x4ac/0x3100 net/sctp/outqueue.c:1209
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:-1 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline]
sctp_do_sm+0x4ee2/0x55f0 net/sctp/sm_sideeffect.c:1170
sctp_primitive_ASSOCIATE+0x91/0xc0 net/sctp/primitive.c:73
sctp_sendmsg_to_asoc+0x14a7/0x1d90 net/sctp/socket.c:1840
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+0x1a5/0x200 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/0xd0 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]
__kmalloc+0x127/0x330 mm/slub.c:4408
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+0x1a5/0x200 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/0xd0 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]
kmalloc include/linux/slab.h:612 [inline]
tomoyo_realpath_from_path+0x118/0x610 security/tomoyo/realpath.c:254
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x23f/0x5d0 security/tomoyo/file.c:822
security_inode_getattr+0xcf/0x120 security/security.c:1348
vfs_getattr+0x26/0x3a0 fs/stat.c:157
vfs_statx+0x14e/0x500 fs/stat.c:225
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat fs/stat.c:411 [inline]
__se_sys_newfstatat fs/stat.c:405 [inline]
__x64_sys_newfstatat+0x15f/0x200 fs/stat.c:405
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
tomoyo_realpath_from_path+0x118/0x610 security/tomoyo/realpath.c:254
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x23f/0x5d0 security/tomoyo/file.c:822
security_inode_getattr+0xcf/0x120 security/security.c:1348
vfs_getattr+0x26/0x3a0 fs/stat.c:157
vfs_statx+0x14e/0x500 fs/stat.c:225
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat fs/stat.c:411 [inline]
__se_sys_newfstatat fs/stat.c:405 [inline]
__x64_sys_newfstatat+0x15f/0x200 fs/stat.c:405
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
Memory state around the buggy address:
ffff8880759bb180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880759bb200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880759bb280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff8880759bb300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880759bb380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
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