linux-kernel - Re: [syzbot] [netfs?] KASAN: slab-use-after-free Write in io_submit

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Message-ID: <67b0027e.050a0220.21dd3.0063.GAE@google.com>
Date: Fri, 14 Feb 2025 18:57:02 -0800
From: syzbot <syzbot+e1dc29a4daf3f8051130@...kaller.appspotmail.com>
To: eadavis@...com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [netfs?] KASAN: slab-use-after-free Write in io_submit_one

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING: refcount bug in netfs_put_subrequest

------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 81 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 1 UID: 0 PID: 81 Comm: kworker/u32:4 Not tainted 6.14.0-rc2-syzkaller-g78a632a2086c-dirty #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events_unbound netfs_read_collection_worker
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 c8 5a f5 fc 84 db 0f 85 66 ff ff ff e8 1b 60 f5 fc c6 05 d7 5c 86 0b 01 90 48 c7 c7 c0 00 d3 8b e8 77 99 b5 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 f8 5f f5 fc 0f b6 1d b2 5c 86 0b 31
RSP: 0018:ffffc9000162fab8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817a1229
RDX: ffff888020af2440 RSI: ffffffff817a1236 RDI: 0000000000000001
RBP: ffff8880305354a0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000002 R12: 0000000000000005
R13: 00000000000006ed R14: 0000000000000001 R15: ffff8880305354a0
FS:  0000000000000000(0000) GS:ffff88806a700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb7675a2f98 CR3: 000000000df80000 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]
 netfs_put_subrequest+0x2c1/0x4d0 fs/netfs/objects.c:230
 netfs_collect_read_results fs/netfs/read_collect.c:300 [inline]
 netfs_read_collection+0x25af/0x3d00 fs/netfs/read_collect.c:422
 netfs_read_collection_worker+0x285/0x350 fs/netfs/read_collect.c:469
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3317 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>


Tested on:

commit:         78a632a2 Merge tag 'pci-v6.14-fixes-3' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=123719a4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c09dc55ba7f798e3
dashboard link: https://syzkaller.appspot.com/bug?extid=e1dc29a4daf3f8051130
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16a667df980000