[syzbot ci] Re: KEYS: Return user session keyring on lookup

[syzbot ci]

syzbot ci has tested the following series

[v2] KEYS: Return user session keyring on lookup
https://lore.kernel.org/all/20261019145624....@kernel.org
* [PATCH v2 1/2] KEYS: Return user session keyring on lookup
* [PATCH v2 2/2] KEYS: Reject keyring creation with overridden credentials

and found the following issue:
general protection fault in keyctl_session_to_parent

Full report is available here:
https://ci.syzbot.org/series/7566814a-52ba-4f0b-b506-d7adf67fda29

***

general protection fault in keyctl_session_to_parent

tree: linux-next
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next
base: 17a7501b9612a52b38bc57e33c7b64636d438bc0
arch: amd64
compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
config: https://ci.syzbot.org/builds/eee373c7-f447-49cf-a350-83830580c7b2/config

Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df]
CPU: 0 UID: 0 PID: 5730 Comm: syz.0.6 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:keyctl_session_to_parent+0x825/0xa30
Code: 35 3b fd e9 fe fa ff ff e8 38 35 3b fd e9 f4 fa ff ff e8 2e 35 3b fd 48 8b 54 24 20 48 81 c2 d8 00 00 00 48 89 d0 48 c1 e8 03 <0f> b6 04 18 84 c0 0f 85 b2 01 00 00 8b 2a 89 ef 8b 5c 24 1c 89 de
RSP: 0018:ffffc9000621fc70 EFLAGS: 00010006
RAX: 000000000000001b RBX: dffffc0000000000 RCX: ffff88810b603c00
RDX: 00000000000000d8 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000c43f7c R12: ffff88811a010000
R13: 0000000000000000 R14: ffff88810c2631a8 R15: 0000000000000000
FS: 00007f7f2068b6c0(0000) GS:ffff88818c4bf000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7f2068aff8 CR3: 000000010cae8000 CR4: 00000000000006f0
Call Trace:
<TASK>
__se_sys_keyctl+0x780/0x9d0
do_syscall_64+0x166/0x520
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7f1f79f559
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:00007f7f2068b028 EFLAGS: 00000246 ORIG_RAX: 00000000000000fa
RAX: ffffffffffffffda RBX: 00007f7f1fa26270 RCX: 00007f7f1f79f559
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000012
RBP: 00007f7f1f836b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7f1fa26308 R14: 00007f7f1fa26270 R15: 00007ffe789f59b8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:keyctl_session_to_parent+0x825/0xa30
Code: 35 3b fd e9 fe fa ff ff e8 38 35 3b fd e9 f4 fa ff ff e8 2e 35 3b fd 48 8b 54 24 20 48 81 c2 d8 00 00 00 48 89 d0 48 c1 e8 03 <0f> b6 04 18 84 c0 0f 85 b2 01 00 00 8b 2a 89 ef 8b 5c 24 1c 89 de
RSP: 0018:ffffc9000621fc70 EFLAGS: 00010006
RAX: 000000000000001b RBX: dffffc0000000000 RCX: ffff88810b603c00
RDX: 00000000000000d8 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000c43f7c R12: ffff88811a010000
R13: 0000000000000000 R14: ffff88810c2631a8 R15: 0000000000000000
FS: 00007f7f2068b6c0(0000) GS:ffff88818c4bf000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7f2068aff8 CR3: 000000010cae8000 CR4: 00000000000006f0


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syz...@syzkaller.appspotmail.com

---
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Notes:
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- To test a new version of the whole series, please send it directly
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- Arguments like custom git repos and branches are not supported.

[Jarkko Sakkinen]

This helps, I save this to my TODO-folder (no time to address this
week).

Br, Jarkko