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SubjectRe: [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write()
On Wed, Feb 17, 2021 at 04:13:58PM +0100, Greg KH wrote:
> On Wed, Feb 17, 2021 at 08:43:47PM +0600, Sabyrzhan Tasbolatov wrote:
> > 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")
>
> 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,

greg k-h

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