[v5.15] general protection fault in rxrpc_kernel_get_srtt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aabd761612db Linux 5.15.215
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=110ccc79580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f161cbc9aef65db0
dashboard link: https://syzkaller.appspot.com/bug?extid=f2fecb79c7f3c172c6c8
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f636f56d3662/disk-aabd7616.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f1a46620f40c/vmlinux-aabd7616.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9b78bb48b022/bzImage-aabd7616.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f2fecb...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 0 PID: 7 Comm: kworker/0:0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: kafsd afs_process_async_call
RIP: 0010:rxrpc_kernel_get_srtt+0x28/0x100 net/rxrpc/peer_object.c:518
Code: 00 00 55 41 57 41 56 41 54 53 48 89 d3 49 89 f6 49 bc 00 00 00 00 00 fc ff df e8 03 6d 72 f8 49 83 c6 18 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 a9 8f b7 f8 4d 8b 36 4d 8d be 98
RSP: 0018:ffffc90000cc7a10 EFLAGS: 00010206
RAX: 0000000000000003 RBX: ffffc90000cc7aa0 RCX: ffff888016e93b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888073e25400
RBP: ffffc90000cc7b10 R08: ffff88805f4eb81f R09: 1ffff1100be9d703
R10: dffffc0000000000 R11: ffffed100be9d704 R12: dffffc0000000000
R13: ffff888073e25400 R14: 0000000000000018 R15: ffff8880739530f0
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32a1cff8 CR3: 00000000570f7000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 00000000e0000011
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
afs_vlserver_probe_result+0x5fd/0xaa0 fs/afs/vl_probe.c:118
afs_deliver_to_call+0xc13/0x1100 fs/afs/rxrpc.c:562
afs_process_async_call+0x7e/0xe0 fs/afs/rxrpc.c:702
process_one_work+0x867/0xff0 kernel/workqueue.c:2310
worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Modules linked in:
---[ end trace 005e64d3758b8681 ]---
RIP: 0010:rxrpc_kernel_get_srtt+0x28/0x100 net/rxrpc/peer_object.c:518
Code: 00 00 55 41 57 41 56 41 54 53 48 89 d3 49 89 f6 49 bc 00 00 00 00 00 fc ff df e8 03 6d 72 f8 49 83 c6 18 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 a9 8f b7 f8 4d 8b 36 4d 8d be 98
RSP: 0018:ffffc90000cc7a10 EFLAGS: 00010206
RAX: 0000000000000003 RBX: ffffc90000cc7aa0 RCX: ffff888016e93b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888073e25400
RBP: ffffc90000cc7b10 R08: ffff88805f4eb81f R09: 1ffff1100be9d703
R10: dffffc0000000000 R11: ffffed100be9d704 R12: dffffc0000000000
R13: ffff888073e25400 R14: 0000000000000018 R15: ffff8880739530f0
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32a1cff8 CR3: 00000000570f7000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 00000000e0000011
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 55 push %rbp
3: 41 57 push %r15
5: 41 56 push %r14
7: 41 54 push %r12
9: 53 push %rbx
a: 48 89 d3 mov %rdx,%rbx
d: 49 89 f6 mov %rsi,%r14
10: 49 bc 00 00 00 00 00 movabs $0xdffffc0000000000,%r12
17: fc ff df
1a: e8 03 6d 72 f8 call 0xf8726d22
1f: 49 83 c6 18 add $0x18,%r14
23: 4c 89 f0 mov %r14,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 f7 mov %r14,%rdi
34: e8 a9 8f b7 f8 call 0xf8b78fe2
39: 4d 8b 36 mov (%r14),%r14
3c: 4d rex.WRB
3d: 8d .byte 0x8d
3e: be .byte 0xbe
3f: 98 cwtl


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