[syzbot] [io-uring?] KMSAN: uninit-value in io_rw_fail (2)

[syzbot] [io-uring?] KMSAN: uninit-value in io_rw_fail (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    9f8413c4a66f Merge tag 'cgroup-for-6.8' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1743d3e4180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=656820e61b758b15
dashboard link: https://syzkaller.appspot.com/bug?extid=0198afa90d8c29ef9557
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/79d9f2f4b065/disk-9f8413c4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cbc68430d9c6/vmlinux-9f8413c4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9740ad9fc172/bzImage-9f8413c4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0198afa90d8c29ef9557@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in io_fixup_rw_res io_uring/rw.c:311 [inline]
BUG: KMSAN: uninit-value in io_rw_fail+0x1a7/0x1b0 io_uring/rw.c:1099
 io_fixup_rw_res io_uring/rw.c:311 [inline]
 io_rw_fail+0x1a7/0x1b0 io_uring/rw.c:1099
 io_req_defer_failed+0x217/0x3e0 io_uring/io_uring.c:1065
 io_queue_sqe_fallback+0x1f4/0x260 io_uring/io_uring.c:2100
 io_submit_state_end io_uring/io_uring.c:2345 [inline]
 io_submit_sqes+0x2b85/0x2ff0 io_uring/io_uring.c:2463
 __do_sys_io_uring_enter io_uring/io_uring.c:3712 [inline]
 __se_sys_io_uring_enter+0x40c/0x42d0 io_uring/io_uring.c:3647
 __x64_sys_io_uring_enter+0x11b/0x1a0 io_uring/io_uring.c:3647
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x6d/0x140 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at:
 slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768
 slab_alloc_node mm/slub.c:3478 [inline]
 __kmem_cache_alloc_node+0x5c9/0x970 mm/slub.c:3517
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc+0x121/0x3c0 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 io_alloc_async_data io_uring/io_uring.c:1780 [inline]
 io_req_prep_async+0x384/0x5a0 io_uring/io_uring.c:1801
 io_queue_sqe_fallback+0x95/0x260 io_uring/io_uring.c:2097
 io_submit_state_end io_uring/io_uring.c:2345 [inline]
 io_submit_sqes+0x2b85/0x2ff0 io_uring/io_uring.c:2463
 __do_sys_io_uring_enter io_uring/io_uring.c:3712 [inline]
 __se_sys_io_uring_enter+0x40c/0x42d0 io_uring/io_uring.c:3647
 __x64_sys_io_uring_enter+0x11b/0x1a0 io_uring/io_uring.c:3647
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x6d/0x140 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

CPU: 0 PID: 5401 Comm: syz-executor.4 Not tainted 6.7.0-syzkaller-00562-g9f8413c4a66f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
=====================================================


---
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 syzkaller@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

Re: [syzbot] [io-uring?] KMSAN: uninit-value in io_rw_fail (2)

[Jens Axboe]

On 2/9/24 3:10 PM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    9f8413c4a66f Merge tag 'cgroup-for-6.8' of git://git.kerne..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1743d3e4180000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=656820e61b758b15
> dashboard link: https://syzkaller.appspot.com/bug?extid=0198afa90d8c29ef9557
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

This was fixed a while back, not sure why an old kernel is being tested. But
in any case, the result of this was just garbage in cqe->res for a request
that was prematurely errored. Nothing to worry about. In any case:

#syz fix: io_uring/rw: ensure io->bytes_done is always initialized

-- 
Jens Axboe

Re: [syzbot] [io-uring?] KMSAN: uninit-value in io_rw_fail (2)

[Alexander Potapenko]

> This was fixed a while back, not sure why an old kernel is being tested. But
> in any case, the result of this was just garbage in cqe->res for a request
> that was prematurely errored. Nothing to worry about. In any case:

Unfortunately KMSAN is broken at head, we're waiting for
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=558c04d9535d9d8911162db4d0d758f8f4cda37b
to reach mainline.