[syzbot] [kernel?] KMSAN: kernel-infoleak in irqentry_exit (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4a50a141f05a Merge tag 'bootconfig-fixes-v7.2-rc1' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13c87bb1580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c2842025f4a17812
dashboard link: https://syzkaller.appspot.com/bug?extid=fb19c2cd5a21000b7336
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/c4b66817b655/disk-4a50a141.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ce2987914219/vmlinux-4a50a141.xz
kernel image: https://storage.googleapis.com/syzbot-assets/61031b19febb/bzImage-4a50a141.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fb19c2...@syzkaller.appspotmail.com

8021q: adding VLAN 0 to HW filter on device bond0
eql: remember to turn off Van-Jacobson compression on your slave devices
=====================================================
BUG: KMSAN: kernel-infoleak in rseq_set_ids_get_csaddr include/linux/rseq_entry.h:502 [inline]
BUG: KMSAN: kernel-infoleak in rseq_update_usr include/linux/rseq_entry.h:536 [inline]
BUG: KMSAN: kernel-infoleak in rseq_exit_user_update include/linux/rseq_entry.h:645 [inline]
BUG: KMSAN: kernel-infoleak in __rseq_exit_to_user_mode_restart include/linux/rseq_entry.h:674 [inline]
BUG: KMSAN: kernel-infoleak in rseq_exit_to_user_mode_restart include/linux/rseq_entry.h:703 [inline]
BUG: KMSAN: kernel-infoleak in exit_to_user_mode_loop kernel/entry/common.c:103 [inline]
BUG: KMSAN: kernel-infoleak in __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
BUG: KMSAN: kernel-infoleak in irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
BUG: KMSAN: kernel-infoleak in irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
BUG: KMSAN: kernel-infoleak in irqentry_exit+0x4a6/0xa40 kernel/entry/common.c:165
rseq_set_ids_get_csaddr include/linux/rseq_entry.h:502 [inline]
rseq_update_usr include/linux/rseq_entry.h:536 [inline]
rseq_exit_user_update include/linux/rseq_entry.h:645 [inline]
__rseq_exit_to_user_mode_restart include/linux/rseq_entry.h:674 [inline]
rseq_exit_to_user_mode_restart include/linux/rseq_entry.h:703 [inline]
exit_to_user_mode_loop kernel/entry/common.c:103 [inline]
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
irqentry_exit+0x4a6/0xa40 kernel/entry/common.c:165
exc_page_fault+0x7e/0xb0 arch/x86/mm/fault.c:1539
asm_exc_page_fault+0x2b/0x30 arch/x86/include/asm/idtentry.h:595

Local variable agg.tmp11.i.i.i created at:
class_fd_constructor include/linux/file.h:83 [inline]
__sys_getsockopt net/socket.c:2497 [inline]
__do_sys_getsockopt net/socket.c:2512 [inline]
__se_sys_getsockopt net/socket.c:2509 [inline]
__x64_sys_getsockopt+0xdb/0x4f0 net/socket.c:2509
x64_sys_call+0x3ab8/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:56

Bytes 1-3 of 4 are uninitialized
Memory access of size 4 starts at ffff88811c49fe78
Data copied to user address 00007fc26f35e680

CPU: 0 UID: 0 PID: 5226 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
=====================================================


---
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