linux-kernel - [syzbot] [io-uring?] memory leak in io_submit

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Message-ID: <692dcb58.a70a0220.2ea503.00b5.GAE@google.com>
Date: Mon, 01 Dec 2025 09:07:36 -0800
From: syzbot <syzbot+641eec6b7af1f62f2b99@...kaller.appspotmail.com>
To: axboe@...nel.dk, io-uring@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [io-uring?] memory leak in io_submit_sqes (5)

Hello,

syzbot found the following issue on:

HEAD commit:    7d0a66e4bb90 Linux 6.18
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=110d0512580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f30cc590c4f6da44
dashboard link: https://syzkaller.appspot.com/bug?extid=641eec6b7af1f62f2b99
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=150d0512580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3e289f3ec7e8/disk-7d0a66e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bf695f1b8080/vmlinux-7d0a66e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/eb2f95cf98c6/bzImage-7d0a66e4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+641eec6b7af1f62f2b99@...kaller.appspotmail.com

2025/12/01 16:45:07 executed programs: 5
BUG: memory leak
unreferenced object 0xffff888112d6b200 (size 248):
  comm "syz.0.17", pid 6070, jiffies 4294944719
  hex dump (first 32 bytes):
    40 f8 56 0d 81 88 ff ff 00 00 00 00 00 00 00 00  @.V.............
    3c 20 00 c0 00 00 00 00 00 00 00 00 00 00 00 00  < ..............
  backtrace (crc 9dd5d643):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4983 [inline]
    kmem_cache_alloc_bulk_noprof+0x220/0x3e0 mm/slub.c:7497
    __io_alloc_req_refill+0x54/0x1a0 io_uring/io_uring.c:1058
    io_alloc_req io_uring/io_uring.h:543 [inline]
    io_submit_sqes+0x584/0xe80 io_uring/io_uring.c:2438
    __do_sys_io_uring_enter+0x83f/0xcf0 io_uring/io_uring.c:3516
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xfa0 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff888112e96200 (size 248):
  comm "syz.0.18", pid 6072, jiffies 4294944721
  hex dump (first 32 bytes):
    40 f8 56 0d 81 88 ff ff 00 00 00 00 00 00 00 00  @.V.............
    3c 20 00 c0 00 00 00 00 00 00 00 00 00 00 00 00  < ..............
  backtrace (crc 79b7669c):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4983 [inline]
    kmem_cache_alloc_bulk_noprof+0x220/0x3e0 mm/slub.c:7497
    __io_alloc_req_refill+0x54/0x1a0 io_uring/io_uring.c:1058
    io_alloc_req io_uring/io_uring.h:543 [inline]
    io_submit_sqes+0x584/0xe80 io_uring/io_uring.c:2438
    __do_sys_io_uring_enter+0x83f/0xcf0 io_uring/io_uring.c:3516
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xfa0 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff888112e5ed00 (size 248):
  comm "syz.0.19", pid 6073, jiffies 4294944722
  hex dump (first 32 bytes):
    40 f8 56 0d 81 88 ff ff 00 00 00 00 00 00 00 00  @.V.............
    3c 20 00 c0 00 00 00 00 00 00 00 00 00 00 00 00  < ..............
  backtrace (crc 11e3e38b):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4983 [inline]
    kmem_cache_alloc_bulk_noprof+0x220/0x3e0 mm/slub.c:7497
    __io_alloc_req_refill+0x54/0x1a0 io_uring/io_uring.c:1058
    io_alloc_req io_uring/io_uring.h:543 [inline]
    io_submit_sqes+0x584/0xe80 io_uring/io_uring.c:2438
    __do_sys_io_uring_enter+0x83f/0xcf0 io_uring/io_uring.c:3516
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xfa0 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff888127618400 (size 248):
  comm "syz.0.20", pid 6127, jiffies 4294945384
  hex dump (first 32 bytes):
    40 f8 56 0d 81 88 ff ff 00 00 00 00 00 00 00 00  @.V.............
    3c 20 00 c0 00 00 00 00 00 00 00 00 00 00 00 00  < ..............
  backtrace (crc b9653957):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4983 [inline]
    kmem_cache_alloc_bulk_noprof+0x220/0x3e0 mm/slub.c:7497
    __io_alloc_req_refill+0x54/0x1a0 io_uring/io_uring.c:1058
    io_alloc_req io_uring/io_uring.h:543 [inline]
    io_submit_sqes+0x584/0xe80 io_uring/io_uring.c:2438
    __do_sys_io_uring_enter+0x83f/0xcf0 io_uring/io_uring.c:3516
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xfa0 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff8881262cf200 (size 248):
  comm "syz.0.21", pid 6128, jiffies 4294945385
  hex dump (first 32 bytes):
    40 f8 56 0d 81 88 ff ff 00 00 00 00 00 00 00 00  @.V.............
    3c 20 00 c0 00 00 00 00 00 00 00 00 00 00 00 00  < ..............
  backtrace (crc 457654b1):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4983 [inline]
    kmem_cache_alloc_bulk_noprof+0x220/0x3e0 mm/slub.c:7497
    __io_alloc_req_refill+0x54/0x1a0 io_uring/io_uring.c:1058
    io_alloc_req io_uring/io_uring.h:543 [inline]
    io_submit_sqes+0x584/0xe80 io_uring/io_uring.c:2438
    __do_sys_io_uring_enter+0x83f/0xcf0 io_uring/io_uring.c:3516
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xfa0 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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