From: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
To: gregkh@linuxfoundation.org
Cc: jirislaby@kernel.org, linux-kernel@vger.kernel.org,
snovitoll@gmail.com,
syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com
Subject: [PATCH v2] tty: fix when iov_iter_count() returns 0 in tty_write()
Date: Wed, 17 Feb 2021 21:55:36 +0600 [thread overview]
Message-ID: <20210217155536.2986178-1-snovitoll@gmail.com> (raw)
In-Reply-To: <YC0zGySVWMKdpulA@kroah.com>
syzbot found WARNING in iov_iter_revert[1] when iov_iter_count() returns 0,
therefore INT_MAX is passed to iov_iter_revert() causing > MAX_RW_COUNT
warning.
static inline ssize_t do_tty_write()
{
..
size_t count = iov_iter_count(from);
..
size_t size = count;
if (ret != size)
iov_iter_revert(from, size-ret);
[1] WARNING: lib/iov_iter.c:1090
Call Trace:
do_tty_write drivers/tty/tty_io.c:967 [inline]
file_tty_write.constprop.0+0x55f/0x8f0 drivers/tty/tty_io.c:1048
call_write_iter include/linux/fs.h:1901 [inline]
new_sync_write+0x426/0x650 fs/read_write.c:518
vfs_write+0x791/0xa30 fs/read_write.c:605
ksys_write+0x12d/0x250 fs/read_write.c:658
Fixes: 9bb48c82aced ("tty: implement write_iter")
Reported-by: syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
---
v2: Fixed "Fixed" tag to proper commit and changed write return to -EFAULT
as this statement is valid, tested via strace:
write(3, NULL, 0) = -1 EFAULT (Bad address)
Updated to -EFAULT, should be a valid exit code as
copy_from_iter(.., .., from) returns -EFAULT as well if *from is invalid
address.
>
> Nit, you need a ' ' before your '(' character here, otherwise the
> linux-next scripts will complain.
> Also, you got the git commit id wrong, so this needs to be fixed up
> anyway. You are pointing to a merge point, I doubt that's what you want
> to point to here, right?
Thanks!
---
drivers/tty/tty_io.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 816e709afa56..e1460cad8b7d 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -905,6 +905,9 @@ static inline ssize_t do_tty_write(
ssize_t ret, written = 0;
unsigned int chunk;
+ if (!count)
+ return -EFAULT;
+
ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
if (ret < 0)
return ret;
--
2.25.1
next prev parent reply other threads:[~2021-02-17 15:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 14:43 [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write() Sabyrzhan Tasbolatov
2021-02-17 15:13 ` Greg KH
2021-02-17 15:15 ` Greg KH
2021-02-17 15:55 ` Sabyrzhan Tasbolatov [this message]
2021-02-19 9:17 ` [PATCH v2] " Jiri Slaby
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