tty: fix when iov_iter_count() returns 0
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: 494e63ee9c("tty: implement write_iter")
Reported-by: syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Change-Id: Ief2f869e7e5d7f3f7e840651389ddf97aeb9b13c
1 file changed
