memory leak in io_submit_sqes (6)

Status: upstream: reported C repro on 2026/08/10 16:51
Subsystems: io-uring block
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+a4ccdd7ebf452e4d4701@syzkaller.appspotmail.com
First crash: 1d11h, last: 1d11h
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ID Workflow Result Correct Bug Created Started Finished Revision
bbcd9aa1 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ memory leak in io_submit_sqes (6) 2026/08/09 11:25 2026/08/09 11:25 2026/08/09 12:25 5d63f80b
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Title Replies (including bot) Last reply
[syzbot] [io-uring?] [block?] memory leak in io_submit_sqes (6) 0 (1) 2026/08/10 16:51
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream memory leak in io_submit_sqes fs io-uring 3 syz, C 2 2171d 2190d 15/29 fixed on 2020/09/16 22:51
upstream memory leak in io_submit_sqes (2) fs io-uring 3 syz, C 1 1987d 1986d 20/29 fixed on 2021/04/09 19:46
upstream memory leak in io_submit_sqes (4) io-uring 3 syz, C 1 1310d 1309d 22/29 fixed on 2023/06/08 14:41
upstream memory leak in io_submit_sqes (5) io-uring 3 syz 3 252d 252d 29/29 fixed on 2026/01/07 12:29
upstream memory leak in io_submit_sqes (3) fs io-uring 3 syz, C 1 1900d 1899d 0/29 auto-obsoleted due to no activity on 2022/10/10 15:32

Sample crash report:
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

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/09 11:11 upstream 06cf61899d64 5d63f80b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-gce-leak memory leak in io_submit_sqes
2026/08/09 11:09 upstream 06cf61899d64 5d63f80b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-gce-leak memory leak in io_submit_sqes
* Struck through repros no longer work on HEAD.