Messages in this thread | | | Date | Wed, 17 Feb 2021 16:13:58 +0100 | From | Greg KH <> | Subject | Re: [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write() |
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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.
> Reported-by: syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com > Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com> > --- > 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..8d6d579ecc3b 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 -EINVAL;
According to the man page for write(2), I think this is the wrong error value to return, unless that is the value that was returned on kernels before the commit listed above.
Can you verify this?
thanks,
greg k-h
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