[Android 5.15] KASAN: stack-out-of-bounds Read in __xfrm_dst_hash

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7e1070528954 Merge android13-5.15 into android13-5.15-lts
git tree: android13-5.15-lts
console output: https://syzkaller.appspot.com/x/log.txt?x=10425322580000
kernel config: https://syzkaller.appspot.com/x/.config?x=deffac0a782f1cb0
dashboard link: https://syzkaller.appspot.com/bug?extid=9edcd664260dd9942e34
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=17049644580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=128d3bfa580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6895df5d7496/disk-7e107052.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/153bd31b2719/vmlinux-7e107052.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d9e2a19c0f4f/bzImage-7e107052.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9edcd6...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: stack-out-of-bounds in jhash2 include/linux/jhash.h:138 [inline]
BUG: KASAN: stack-out-of-bounds in __xfrm6_addr_hash net/xfrm/xfrm_hash.h:16 [inline]
BUG: KASAN: stack-out-of-bounds in __xfrm6_daddr_saddr_hash net/xfrm/xfrm_hash.h:29 [inline]
BUG: KASAN: stack-out-of-bounds in __xfrm_dst_hash+0x399/0x480 net/xfrm/xfrm_hash.h:95
Read of size 4 at addr ffffc900001d0ad8 by task swapper/1/0

CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<IRQ>
__dump_stack+0x21/0x30 lib/dump_stack.c:88
dump_stack_lvl+0x110/0x170 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_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
jhash2 include/linux/jhash.h:138 [inline]
__xfrm6_addr_hash net/xfrm/xfrm_hash.h:16 [inline]
__xfrm6_daddr_saddr_hash net/xfrm/xfrm_hash.h:29 [inline]
__xfrm_dst_hash+0x399/0x480 net/xfrm/xfrm_hash.h:95
xfrm_dst_hash net/xfrm/xfrm_state.c:63 [inline]
xfrm_state_find+0x28a/0x2a10 net/xfrm/xfrm_state.c:1092
xfrm_tmpl_resolve_one net/xfrm/xfrm_policy.c:2396 [inline]
xfrm_tmpl_resolve net/xfrm/xfrm_policy.c:2441 [inline]
xfrm_resolve_and_create_bundle+0x697/0x29f0 net/xfrm/xfrm_policy.c:2734
xfrm_bundle_lookup net/xfrm/xfrm_policy.c:2969 [inline]
xfrm_lookup_with_ifid+0x4e9/0x2080 net/xfrm/xfrm_policy.c:3100
xfrm_lookup net/xfrm/xfrm_policy.c:3197 [inline]
xfrm_lookup_route+0x3c/0x170 net/xfrm/xfrm_policy.c:3208
ip_route_output_flow+0x1f8/0x2f0 net/ipv4/route.c:2905
ip_route_output_ports include/net/route.h:169 [inline]
igmpv3_newpack+0x280/0xcd0 net/ipv4/igmp.c:372
add_grhead+0x75/0x2e0 net/ipv4/igmp.c:443
add_grec+0x116c/0x1410 net/ipv4/igmp.c:577
igmpv3_send_cr net/ipv4/igmp.c:714 [inline]
igmp_ifc_timer_expire+0x89e/0xf80 net/ipv4/igmp.c:813
call_timer_fn+0x38/0x290 kernel/time/timer.c:1457
expire_timers kernel/time/timer.c:1502 [inline]
__run_timers+0x650/0x9e0 kernel/time/timer.c:1773
run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1786
handle_softirqs+0x250/0x560 kernel/softirq.c:583
__do_softirq kernel/softirq.c:621 [inline]
invoke_softirq kernel/softirq.c:443 [inline]
__irq_exit_rcu+0x52/0xf0 kernel/softirq.c:670
irq_exit_rcu+0x9/0x10 kernel/softirq.c:682
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:default_idle+0xf/0x20 arch/x86/kernel/process.c:730
Code: ff 4c 89 f7 e8 d2 27 f5 fc e9 3d ff ff ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 55 48 89 e5 66 90 0f 00 2d 93 93 51 00 fb f4 <5d> c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41
RSP: 0018:ffffc90000157d98 EFLAGS: 00000242
RAX: 0000000000002d8c RBX: ffff88810030a780 RCX: 0000000000002d8c
RDX: 0000000000000001 RSI: ffffffff85639520 RDI: ffffffff856394e0
RBP: ffffc90000157d98 R08: ffff8881f7138c73 R09: 1ffff1103ee2718e
R10: dffffc0000000000 R11: ffffed103ee2718f R12: 1ffff110200614f0
R13: 0000000000000001 R14: 0000000000000000 R15: dffffc0000000000
arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:721
default_idle_call+0x71/0x1d0 kernel/sched/idle.c:112
cpuidle_idle_call kernel/sched/idle.c:194 [inline]
do_idle+0x1dc/0x570 kernel/sched/idle.c:306
cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:403
start_secondary+0x2e6/0x3a0 arch/x86/kernel/smpboot.c:281
secondary_startup_64_no_verify+0xb1/0xbb
</TASK>


Memory state around the buggy address:
ffffc900001d0980: f8 f8 f3 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
ffffc900001d0a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900001d0a80: f1 f1 f1 f1 00 00 00 00 00 00 00 f3 f3 f3 f3 f3
^
ffffc900001d0b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc900001d0b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
----------------
Code disassembly (best guess):
0: ff 4c 89 f7 decl -0x9(%rcx,%rcx,4)
4: e8 d2 27 f5 fc call 0xfcf527db
9: e9 3d ff ff ff jmp 0xffffff4b
e: 00 00 add %al,(%rax)
10: cc int3
11: cc int3
12: 00 00 add %al,(%rax)
14: cc int3
15: cc int3
16: 00 00 add %al,(%rax)
18: cc int3
19: cc int3
1a: 00 55 48 add %dl,0x48(%rbp)
1d: 89 e5 mov %esp,%ebp
1f: 66 90 xchg %ax,%ax
21: 0f 00 2d 93 93 51 00 verw 0x519393(%rip) # 0x5193bb
28: fb sti
29: f4 hlt
* 2a: 5d pop %rbp <-- trapping instruction
2b: c3 ret
2c: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1)
33: 00 00 00
36: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
3b: 55 push %rbp
3c: 48 89 e5 mov %rsp,%rbp
3f: 41 rex.B


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