[syzbot] [io-uring?] KMSAN: uninit-value in io_issue_sqe

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 614da38e2f7a Merge tag 'hid-for-linus-2024051401' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11b9b972980000
kernel config: https://syzkaller.appspot.com/x/.config?x=f5d2cbf33633f507
dashboard link: https://syzkaller.appspot.com/bug?extid=b1647099e82b3b349fbf
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/89eafb874b71/disk-614da38e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/356000512ad9/vmlinux-614da38e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/839c73939115/bzImage-614da38e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b16470...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in io_req_cqe_overflow io_uring/io_uring.c:810 [inline]
BUG: KMSAN: uninit-value in io_req_complete_post io_uring/io_uring.c:937 [inline]
BUG: KMSAN: uninit-value in io_issue_sqe+0x1f1b/0x22c0 io_uring/io_uring.c:1763
io_req_cqe_overflow io_uring/io_uring.c:810 [inline]
io_req_complete_post io_uring/io_uring.c:937 [inline]
io_issue_sqe+0x1f1b/0x22c0 io_uring/io_uring.c:1763
io_wq_submit_work+0xa17/0xeb0 io_uring/io_uring.c:1860
io_worker_handle_work+0xc04/0x2000 io_uring/io-wq.c:597
io_wq_worker+0x447/0x1410 io_uring/io-wq.c:651
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was stored to memory at:
io_req_set_res io_uring/io_uring.h:215 [inline]
io_recv_finish+0xf10/0x1560 io_uring/net.c:861
io_recv+0x12ec/0x1ea0 io_uring/net.c:1175
io_issue_sqe+0x429/0x22c0 io_uring/io_uring.c:1751
io_wq_submit_work+0xa17/0xeb0 io_uring/io_uring.c:1860
io_worker_handle_work+0xc04/0x2000 io_uring/io-wq.c:597
io_wq_worker+0x447/0x1410 io_uring/io-wq.c:651
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
slab_post_alloc_hook mm/slub.c:3877 [inline]
slab_alloc_node mm/slub.c:3918 [inline]
__do_kmalloc_node mm/slub.c:4038 [inline]
__kmalloc+0x6e4/0x1060 mm/slub.c:4052
kmalloc include/linux/slab.h:632 [inline]
io_alloc_async_data+0xc0/0x220 io_uring/io_uring.c:1662
io_msg_alloc_async io_uring/net.c:166 [inline]
io_recvmsg_prep_setup io_uring/net.c:725 [inline]
io_recvmsg_prep+0xbe8/0x1a20 io_uring/net.c:806
io_init_req io_uring/io_uring.c:2135 [inline]
io_submit_sqe io_uring/io_uring.c:2182 [inline]
io_submit_sqes+0x1135/0x2f10 io_uring/io_uring.c:2335
__do_sys_io_uring_enter io_uring/io_uring.c:3246 [inline]
__se_sys_io_uring_enter+0x40f/0x3c80 io_uring/io_uring.c:3183
__x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3183
x64_sys_call+0x2c0/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:427
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 PID: 7410 Comm: iou-wrk-7408 Not tainted 6.9.0-syzkaller-02707-g614da38e2f7a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
=====================================================


---
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

[Jens Axboe]

On 5/27/24 7:22 AM, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 614da38e2f7a Merge tag 'hid-for-linus-2024051401' of git:/..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11b9b972980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=f5d2cbf33633f507
> dashboard link: https://syzkaller.appspot.com/bug?extid=b1647099e82b3b349fbf
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/89eafb874b71/disk-614da38e.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/356000512ad9/vmlinux-614da38e.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/839c73939115/bzImage-614da38e.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b16470...@syzkaller.appspotmail.com
>
> =====================================================
> BUG: KMSAN: uninit-value in io_req_cqe_overflow io_uring/io_uring.c:810 [inline]
> BUG: KMSAN: uninit-value in io_req_complete_post io_uring/io_uring.c:937 [inline]
> BUG: KMSAN: uninit-value in io_issue_sqe+0x1f1b/0x22c0 io_uring/io_uring.c:1763

Should be fixed by:

https://lore.kernel.org/io-uring/c52d9b19-7fd7-4fb1...@kernel.dk/

#syz fix: io_uring/net: assign kmsg inq/flags before buffer selection

--
Jens Axboe