Messages in this thread | | | From | Linus Torvalds <> | Date | Sat, 20 Feb 2021 16:45:40 -0800 | Subject | Re: WARNING in iov_iter_revert (2) |
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[ Let's see how long this lasts, but I've got a generator for the laptop, and hopefully I'll be able to start doing pulls tonight, and get "real" power tomorrow ]
On Sat, Feb 20, 2021 at 11:30 AM Al Viro <viro@zeniv.linux.org.uk> wrote: > > IOW, it's not iov_iter_revert() being weird or do_tty_write() misuing it - > it's tpk_write() playing silly buggers.
Ok, that's actually not as bad I was was afraid it might be.
> Do we want to preserve that weirdness of /dev/ttyprintk writes? > That's orthogonal to the iov_iter uses in there.
I don't think the ttyprintk weirdness was intentional. I'd fix that, but in the meantime clearly we should make do_tty_write() protect against this insanity, and do something like
--- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -961,6 +961,9 @@ static inline ssize_t do_tty_write( ret = write(tty, file, tty->write_buf, size); if (ret <= 0) break; + /* ttyprintk historical oddity */ + if (ret > size) + break;
/* FIXME! Have Al check this! */ if (ret != size)
in there. Because right now we clearly do strange and not-so-wonderful things if the write routine returns a bigger value than it was passed.. Not limited to that iov_iter_revert() thing, but the whole loop.
Comments?
Linus
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