[v5.15] KASAN: slab-out-of-bounds Read in __xfrm_decode_session (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0c935c049b5c Linux 5.15.179
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1316d198580000
kernel config: https://syzkaller.appspot.com/x/.config?x=98c228fbc016eb3a
dashboard link: https://syzkaller.appspot.com/bug?extid=b7fd2685e7d9ce85ae1a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d5477072f336/disk-0c935c04.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/77d15907ffb3/vmlinux-0c935c04.xz
kernel image: https://storage.googleapis.com/syzbot-assets/efe5d79cb16a/Image-0c935c04.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b7fd26...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in decode_session6 net/xfrm/xfrm_policy.c:3410 [inline]
BUG: KASAN: slab-out-of-bounds in __xfrm_decode_session+0x1520/0x1d20 net/xfrm/xfrm_policy.c:3517
Read of size 1 at addr ffff0000d0bdb557 by task syz.1.1299/7277

CPU: 0 PID: 7277 Comm: syz.1.1299 Not tainted 5.15.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
print_address_description+0x7c/0x3f0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:434 [inline]
kasan_report+0x174/0x1e4 mm/kasan/report.c:451
__asan_report_load1_noabort+0x44/0x50 mm/kasan/report_generic.c:306
decode_session6 net/xfrm/xfrm_policy.c:3410 [inline]
__xfrm_decode_session+0x1520/0x1d20 net/xfrm/xfrm_policy.c:3517
xfrm_decode_session_reverse include/net/xfrm.h:1177 [inline]
icmpv6_route_lookup+0x398/0x558 net/ipv6/icmp.c:394
icmp6_send+0xe18/0x1b1c net/ipv6/icmp.c:601
__icmpv6_send include/linux/icmpv6.h:28 [inline]
icmpv6_send include/linux/icmpv6.h:49 [inline]
ip6_link_failure+0x44/0x4a8 net/ipv6/route.c:2788
dst_link_failure include/net/dst.h:422 [inline]
ip6_tnl_xmit+0x1014/0x22a8 net/ipv6/ip6_tunnel.c:1275
ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1391 [inline]
ip6_tnl_start_xmit+0xd60/0x13d8 net/ipv6/ip6_tunnel.c:1440
__netdev_start_xmit include/linux/netdevice.h:5027 [inline]
netdev_start_xmit include/linux/netdevice.h:5041 [inline]
xmit_one net/core/dev.c:3648 [inline]
dev_hard_start_xmit+0x2bc/0x92c net/core/dev.c:3664
sch_direct_xmit+0x2e0/0x484 net/sched/sch_generic.c:342
qdisc_restart net/sched/sch_generic.c:407 [inline]
__qdisc_run+0x878/0x1fc0 net/sched/sch_generic.c:415
__dev_xmit_skb net/core/dev.c:3941 [inline]
__dev_queue_xmit+0x1038/0x2ac8 net/core/dev.c:4252
dev_queue_xmit+0x24/0x34 net/core/dev.c:4320
neigh_connected_output+0x334/0x378 net/core/neighbour.c:1533
neigh_output include/net/neighbour.h:509 [inline]
ip6_finish_output2+0x1360/0x1cec net/ipv6/ip6_output.c:130
__ip6_finish_output+0x580/0x6ec net/ipv6/ip6_output.c:201
ip6_finish_output+0x40/0x218 net/ipv6/ip6_output.c:211
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip6_output+0x274/0x594 net/ipv6/ip6_output.c:234
dst_output include/net/dst.h:452 [inline]
ip6_local_out+0x120/0x160 net/ipv6/output_core.c:161
ip6_send_skb+0x1a8/0x584 net/ipv6/ip6_output.c:1951
udp_v6_send_skb+0x8ac/0x1474 net/ipv6/udp.c:1285
udpv6_sendmsg+0x1a00/0x2850 net/ipv6/udp.c:1586
inet6_sendmsg+0xb4/0xd8 net/ipv6/af_inet6.c:667
sock_sendmsg_nosec net/socket.c:704 [inline]
__sock_sendmsg net/socket.c:716 [inline]
____sys_sendmsg+0x584/0x870 net/socket.c:2436
___sys_sendmsg+0x214/0x294 net/socket.c:2490
__sys_sendmmsg+0x23c/0x648 net/socket.c:2576
__do_sys_sendmmsg net/socket.c:2605 [inline]
__se_sys_sendmmsg net/socket.c:2602 [inline]
__arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2602
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

Allocated by task 1:
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+0xbc/0xfc mm/kasan/common.c:513
__kasan_kmalloc+0x10/0x1c mm/kasan/common.c:522
kasan_kmalloc include/linux/kasan.h:264 [inline]
kmem_cache_alloc_trace+0x27c/0x47c mm/slub.c:3247
kmalloc include/linux/slab.h:591 [inline]
kzalloc include/linux/slab.h:721 [inline]
cec_allocate_adapter+0xa8/0x4e4 drivers/media/cec/core/cec-core.c:254
vivid_cec_alloc_adap+0xec/0x150 drivers/media/test-drivers/vivid/vivid-cec.c:284
vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:1950 [inline]
vivid_probe+0x40fc/0x6b50 drivers/media/test-drivers/vivid/vivid-core.c:2031
platform_probe+0x148/0x1c0 drivers/base/platform.c:1391
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x26c/0xaec drivers/base/dd.c:595
__driver_probe_device+0x194/0x3b4 drivers/base/dd.c:755
driver_probe_device+0x78/0x34c drivers/base/dd.c:785
__driver_attach+0x3ec/0x5ec drivers/base/dd.c:1164
bus_for_each_dev+0x14c/0x1cc drivers/base/bus.c:303
driver_attach+0x4c/0x5c drivers/base/dd.c:1181
bus_add_driver+0x2ec/0x570 drivers/base/bus.c:620
driver_register+0x200/0x374 drivers/base/driver.c:240
__platform_driver_register+0x74/0x8c drivers/base/platform.c:858
vivid_init+0x4c/0x8c drivers/media/test-drivers/vivid/vivid-core.c:2161
do_one_initcall+0x234/0x990 init/main.c:1302
do_initcall_level+0x154/0x214 init/main.c:1375
do_initcalls+0x58/0xac init/main.c:1391
do_basic_setup+0x8c/0xa0 init/main.c:1410
kernel_init_freeable+0x460/0x640 init/main.c:1615
kernel_init+0x24/0x294 init/main.c:1506
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

The buggy address belongs to the object at ffff0000d0bda000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1367 bytes to the right of
4096-byte region [ffff0000d0bda000, ffff0000d0bdb000)
The buggy address belongs to the page:
page:00000000afad9f46 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x110bd8
head:00000000afad9f46 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 dead000000000100 dead000000000122 ffff0000c0002a80
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff0000d0bdb400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff0000d0bdb480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000d0bdb500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff0000d0bdb580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff0000d0bdb600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.