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tty_open can return to userspace holding tty_mutex

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__tty_open could return (to userspace) holding the tty_mutex thanks to a
regression introduced by 4a2b5fddd53b80efcb3266ee36e23b8de28e761a ("Move
tty lookup/reopen to caller").

This was found by bisecting an fsfuzzer problem.  Admittedly I have no
idea how it managed to tickle this 100% reliably, but it is clearly a
regression and when hit leaves the box in a completely unusable state.
This patch lets the fsfuzzer test complete every time.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric Paris 2009-01-27 11:50:37 +00:00 committed by Linus Torvalds
parent 5ee8100721
commit 808ffa3d30
1 changed files with 3 additions and 1 deletions
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4
drivers/char/tty_io.c
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@ -1817,8 +1817,10 @@ got_driver:
/* check whether we're reopening an existing tty */
tty = tty_driver_lookup_tty(driver, inode, index);
if (IS_ERR(tty))
if (IS_ERR(tty)) {
mutex_unlock(&tty_mutex);
return PTR_ERR(tty);
}
}
if (tty) {