[syzbot] [io-uring?] [block?] memory leak in io_submit_sqes (6)

[syzbot] [io-uring?] [block?] memory leak in io_submit_sqes (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    06cf61899d64 Merge tag 'x86-urgent-2026-08-08' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=118c1132580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6843f8fd2336602d
dashboard link: https://syzkaller.appspot.com/bug?extid=a4ccdd7ebf452e4d4701
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=128c5fb9580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15b37fb9580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e023ff6ad9bc/disk-06cf6189.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ea49527ba5df/vmlinux-06cf6189.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e3d6468d0490/bzImage-06cf6189.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a4ccdd7ebf452e4d4701@syzkaller.appspotmail.com

BUG: memory leak
unreferenced object 0xffff888112726000 (size 248):
  comm "syz.0.17", pid 5956, jiffies 4294942148
  hex dump (first 32 bytes):
    80 5d 3a 0e 81 88 ff ff d0 03 59 15 81 88 ff ff  .]:.......Y.....
    04 75 20 c0 02 00 00 80 00 00 00 00 00 00 00 00  .u .............
  backtrace (crc e2966ca0):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4597 [inline]
    kmem_cache_alloc_bulk_noprof+0x272/0x3f0 mm/slub.c:7435
    __io_alloc_req_refill+0x4a/0x150 io_uring/io_uring.c:988
    io_alloc_req io_uring/io_uring.h:536 [inline]
    io_submit_sqes.cold+0x16e/0x20b io_uring/io_uring.c:2046
    __do_sys_io_uring_enter+0x56d/0xd60 io_uring/io_uring.c:2646
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xf8/0x610 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff8881155903c0 (size 192):
  comm "syz.0.17", pid 5956, jiffies 4294942148
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    2e 20 00 00 03 00 00 00 04 75 20 c0 00 00 00 00  . .......u .....
  backtrace (crc db88fe21):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4597 [inline]
    slab_alloc_node mm/slub.c:4917 [inline]
    __do_kmalloc_node mm/slub.c:5333 [inline]
    __kmalloc_noprof+0x3bf/0x550 mm/slub.c:5359
    _kmalloc_noprof include/linux/slab.h:992 [inline]
    io_cache_alloc_new+0x20/0x80 io_uring/alloc_cache.c:40
    io_cache_alloc io_uring/alloc_cache.h:61 [inline]
    io_uring_alloc_async_data io_uring/io_uring.h:355 [inline]
    io_uring_cmd_prep+0x157/0x1f0 io_uring/uring_cmd.c:208
    io_init_req io_uring/io_uring.c:1842 [inline]
    io_submit_sqe io_uring/io_uring.c:1889 [inline]
    io_submit_sqes+0x446/0xd00 io_uring/io_uring.c:2057
    __do_sys_io_uring_enter+0x56d/0xd60 io_uring/io_uring.c:2646
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xf8/0x610 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff888112726100 (size 248):
  comm "syz.0.18", pid 5972, jiffies 4294942449
  hex dump (first 32 bytes):
    80 d7 55 02 81 88 ff ff d0 a0 50 15 81 88 ff ff  ..U.......P.....
    04 75 20 c0 02 00 00 80 00 00 00 00 00 00 00 00  .u .............
  backtrace (crc dcaddc4c):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4597 [inline]
    kmem_cache_alloc_bulk_noprof+0x272/0x3f0 mm/slub.c:7435
    __io_alloc_req_refill+0x4a/0x150 io_uring/io_uring.c:988
    io_alloc_req io_uring/io_uring.h:536 [inline]
    io_submit_sqes.cold+0x16e/0x20b io_uring/io_uring.c:2046
    __do_sys_io_uring_enter+0x56d/0xd60 io_uring/io_uring.c:2646
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xf8/0x610 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

connection error: failed to recv *flatrpc.ExecutorMessageRawT: EOF


---
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 syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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

Forwarded: io_uring/cmd: don't skip completion for a non-armed multishot uring_cmd

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: io_uring/cmd: don't skip completion for a non-armed multishot uring_cmd
Author: vasilisalmpanis@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git dad19b6f6336e1587b0f767d5b4e2b5543224b43

diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index c14c22cff49e..a2899a852879 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -269,7 +269,8 @@ int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags)
 	}
 
 	ret = file->f_op->uring_cmd(ioucmd, issue_flags);
-	if (ioucmd->flags & IORING_URING_CMD_MULTISHOT) {
+	if ((ioucmd->flags & IORING_URING_CMD_MULTISHOT) &&
+	    (req->flags & REQ_F_APOLL_MULTISHOT)) {
 		if (ret >= 0)
 			return IOU_ISSUE_SKIP_COMPLETE;
 	}