linux-kernel - [syzbot] [fs?] WARNING: refcount bug in io_submit

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Message-ID: <67aa3955.050a0220.110943.0031.GAE@google.com>
Date: Mon, 10 Feb 2025 09:37:25 -0800
From: syzbot <syzbot+fbb8bdfedfaab15a3895@...kaller.appspotmail.com>
To: bcrl@...ck.org, brauner@...nel.org, jack@...e.cz, linux-aio@...ck.org, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: [syzbot] [fs?] WARNING: refcount bug in io_submit_one

Hello,

syzbot found the following issue on:

HEAD commit:    69b54314c975 Merge tag 'kbuild-fixes-v6.14' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1508bb18580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a7ddf49cf33ba213
dashboard link: https://syzkaller.appspot.com/bug?extid=fbb8bdfedfaab15a3895
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=168cd1b0580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=134698e4580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-69b54314.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2d0a58d1d655/vmlinux-69b54314.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b99949b40299/bzImage-69b54314.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fbb8bdfedfaab15a3895@...kaller.appspotmail.com

netfs: Couldn't get user pages (rc=-14)
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 3 PID: 6084 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 3 UID: 0 PID: 6084 Comm: syz-executor338 Not tainted 6.14.0-rc1-syzkaller-00276-g69b54314c975 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 78 71 f5 fc 84 db 0f 85 66 ff ff ff e8 cb 76 f5 fc c6 05 e5 68 86 0b 01 90 48 c7 c7 00 fb d2 8b e8 97 b2 b5 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 a8 76 f5 fc 0f b6 1d c0 68 86 0b 31
RSP: 0018:ffffc9000435fc68 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817a1159
RDX: ffff888030b44880 RSI: ffffffff817a1166 RDI: 0000000000000001
RBP: ffff888031bf8488 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: ffff88802cd8f700 R14: ffff888031bf83c0 R15: ffff888031bf8478
FS:  00005555830ae380(0000) GS:ffff88806a900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f51c9f3f000 CR3: 0000000028d22000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_sub_and_test include/linux/refcount.h:275 [inline]
 __refcount_dec_and_test include/linux/refcount.h:307 [inline]
 refcount_dec_and_test include/linux/refcount.h:325 [inline]
 iocb_put fs/aio.c:1208 [inline]
 io_submit_one+0x103f/0x1da0 fs/aio.c:2055
 __do_sys_io_submit fs/aio.c:2111 [inline]
 __se_sys_io_submit fs/aio.c:2081 [inline]
 __x64_sys_io_submit+0x1b2/0x340 fs/aio.c:2081
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f51c9f80ee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdfc54a368 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 00004000000004c0 RCX: 00007f51c9f80ee9
RDX: 00004000000002c0 RSI: 0000000000000001 RDI: 00007f51c9f3f000
RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdfc54a380
R13: 00007ffdfc54a3a0 R14: 000000000000bf9c R15: 00007ffdfc54a37c
 </TASK>


---
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