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Mon, 12 Jan 2026 11:36:01 -0800 (PST) Message-ID: Date: Mon, 12 Jan 2026 12:36:00 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [io-uring?] memory leak in iovec_from_user (3) To: syzbot , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <69653c1e.050a0220.eaf7.00c9.GAE@google.com> Content-Language: en-US From: Jens Axboe In-Reply-To: <69653c1e.050a0220.eaf7.00c9.GAE@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/12/26 11:23 AM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 7143203341dc Merge tag 'libcrypto-for-linus' of git://git... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=177fd9fc580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=87bc41cae23d2144 > dashboard link: https://syzkaller.appspot.com/bug?extid=abecd272a5e56fcef099 > 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=12f4399a580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11ab3c3a580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/1efe18c6d01c/disk-71432033.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/a5a0b8a88b2b/vmlinux-71432033.xz > kernel image: https://storage.googleapis.com/syzbot-assets/5bd4c64b0a42/bzImage-71432033.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+abecd272a5e56fcef099@syzkaller.appspotmail.com I can't reproduce this, and I have a sneaking suspicion that this is mostly just timing on kmemleak scanning. I've seen that a few times. Just running your reproducer and I see: root@debian:~# cat /sys/kernel/debug/kmemleak unreferenced object 0xff110000964a6200 (size 200): comm "kworker/u32:7", pid 1149, jiffies 4294971353 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 c0 92 73 00 01 00 11 ff ..........s..... 01 30 90 00 00 05 04 40 00 00 00 00 01 00 00 00 .0.....@........ backtrace (crc 38936ccb): kmem_cache_alloc_noprof+0x3fe/0x580 mempool_alloc_noprof+0xb9/0x190 bio_alloc_bioset+0x561/0x760 submit_bh_wbc+0x130/0x250 __block_write_full_folio+0x3ad/0x720 block_write_full_folio+0x14c/0x180 blkdev_writepages+0x6c/0xd0 do_writepages+0xe9/0x1f0 __writeback_single_inode+0x5e/0x600 writeback_sb_inodes+0x2ea/0x850 __writeback_inodes_wb+0x5c/0x150 wb_writeback+0x382/0x4d0 wb_workfn+0x4d2/0x640 process_one_work+0x260/0x580 worker_thread+0x2b3/0x4e0 kthread+0x161/0x310 which are obviously temporal, and a whole bunch of the same reports, in fact there is: root@debian:~# cat /sys/kernel/debug/kmemleak | wc -l 264 lines in there. Then let's trigger a new scan: root@debian:~# echo scan > /sys/kernel/debug/kmemleak root@debian:~# cat /sys/kernel/debug/kmemleak | wc -l 0 and they are all gone. #syz invalid -- Jens Axboe