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Message-ID: <004e2f64-cf4e-2490-ed2c-29c073f76704@kernel.dk>
Date:   Sat, 16 Apr 2022 20:17:02 -0600
MIME-Version: 1.0
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Subject: Re: [syzbot] memory leak in iovec_from_user
Content-Language: en-US
To:     syzbot <syzbot+96b43810dfe9c3bb95ed@syzkaller.appspotmail.com>,
        asml.silence@gmail.com, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
References: <000000000000951a1505dccf8b73@google.com>
From:   Jens Axboe <axboe@kernel.dk>
In-Reply-To: <000000000000951a1505dccf8b73@google.com>
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On 4/16/22 7:27 PM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    ce522ba9ef7e Linux 5.18-rc2
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14225724f00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=b8f1a3425e05af27
> dashboard link: https://syzkaller.appspot.com/bug?extid=96b43810dfe9c3bb95ed
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13c45d88f00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17b428af700000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+96b43810dfe9c3bb95ed@syzkaller.appspotmail.com
> 
> executing program
> BUG: memory leak
> unreferenced object 0xffff88810d698300 (size 192):
>   comm "syz-executor156", pid 3595, jiffies 4294944234 (age 12.580s)
>   hex dump (first 32 bytes):
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffff823357be>] kmalloc_array include/linux/slab.h:621 [inline]
>     [<ffffffff823357be>] iovec_from_user lib/iov_iter.c:1922 [inline]
>     [<ffffffff823357be>] iovec_from_user+0x13e/0x280 lib/iov_iter.c:1905
>     [<ffffffff82335945>] __import_iovec+0x45/0x250 lib/iov_iter.c:1948
>     [<ffffffff81668c8e>] __io_import_iovec+0xfe/0x800 fs/io_uring.c:3497
>     [<ffffffff8166d92f>] io_import_iovec fs/io_uring.c:3508 [inline]
>     [<ffffffff8166d92f>] io_read+0x59f/0x880 fs/io_uring.c:3803
>     [<ffffffff816727b4>] io_issue_sqe+0x364/0x3270 fs/io_uring.c:7122
>     [<ffffffff816761c3>] __io_queue_sqe fs/io_uring.c:7489 [inline]
>     [<ffffffff816761c3>] io_queue_sqe fs/io_uring.c:7531 [inline]
>     [<ffffffff816761c3>] io_submit_sqe fs/io_uring.c:7736 [inline]
>     [<ffffffff816761c3>] io_submit_sqes+0x553/0x3030 fs/io_uring.c:7842
>     [<ffffffff81679390>] __do_sys_io_uring_enter+0x6f0/0x1100 fs/io_uring.c:10780
>     [<ffffffff8451ca25>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>     [<ffffffff8451ca25>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>     [<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> BUG: memory leak
> unreferenced object 0xffff88810d6983c0 (size 192):
>   comm "syz-executor156", pid 3603, jiffies 4294944759 (age 7.330s)
>   hex dump (first 32 bytes):
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffff823357be>] kmalloc_array include/linux/slab.h:621 [inline]
>     [<ffffffff823357be>] iovec_from_user lib/iov_iter.c:1922 [inline]
>     [<ffffffff823357be>] iovec_from_user+0x13e/0x280 lib/iov_iter.c:1905
>     [<ffffffff82335945>] __import_iovec+0x45/0x250 lib/iov_iter.c:1948
>     [<ffffffff81668c8e>] __io_import_iovec+0xfe/0x800 fs/io_uring.c:3497
>     [<ffffffff8166d92f>] io_import_iovec fs/io_uring.c:3508 [inline]
>     [<ffffffff8166d92f>] io_read+0x59f/0x880 fs/io_uring.c:3803
>     [<ffffffff816727b4>] io_issue_sqe+0x364/0x3270 fs/io_uring.c:7122
>     [<ffffffff816761c3>] __io_queue_sqe fs/io_uring.c:7489 [inline]
>     [<ffffffff816761c3>] io_queue_sqe fs/io_uring.c:7531 [inline]
>     [<ffffffff816761c3>] io_submit_sqe fs/io_uring.c:7736 [inline]
>     [<ffffffff816761c3>] io_submit_sqes+0x553/0x3030 fs/io_uring.c:7842
>     [<ffffffff81679390>] __do_sys_io_uring_enter+0x6f0/0x1100 fs/io_uring.c:10780
>     [<ffffffff8451ca25>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>     [<ffffffff8451ca25>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>     [<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae


diff --git a/fs/io_uring.c b/fs/io_uring.c
index 659f8ecba5b7..d4feb5ca63ba 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3825,8 +3825,10 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
 		iovec = NULL;
 	}
 	ret = io_rw_init_file(req, FMODE_READ);
-	if (unlikely(ret))
+	if (unlikely(ret)) {
+		kfree(iovec);
 		return ret;
+	}
 	req->result = iov_iter_count(&s->iter);
 
 	if (force_nonblock) {
@@ -3951,8 +3953,10 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
 		iovec = NULL;
 	}
 	ret = io_rw_init_file(req, FMODE_WRITE);
-	if (unlikely(ret))
+	if (unlikely(ret)) {
+		kfree(iovec);
 		return ret;
+	}
 	req->result = iov_iter_count(&s->iter);
 
 	if (force_nonblock) {

-- 
Jens Axboe