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

[syzbot <syzbot+a4ccdd7ebf452e4d4701@syzkaller.appspotmail.com>]

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


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