floppy: fix lock_fdc() signal handling
floppy_revalidate() doesn't perform any error handling on lock_fdc() result. lock_fdc() might actually be interrupted by a signal (it waits for fdc becoming non-busy interruptibly). In such case, floppy_revalidate() proceeds as if it had claimed the lock, but it fact it doesn't. In case of multiple threads trying to open("/dev/fdX"), this leads to serious corruptions all over the place, because all of a sudden there is no critical section protection (that'd otherwise be guaranteed by locked fd) whatsoever. While at this, fix the fact that the 'interruptible' parameter to lock_fdc() doesn't make any sense whatsoever, because we always wait interruptibly anyway. Most of the lock_fdc() callsites do properly handle error (and propagate EINTR), but floppy_revalidate() and floppy_check_events() don't. Fix this. Spotted by 'syzkaller' tool. Reported-by: NDmitry Vyukov <dvyukov@google.com> Tested-by: NDmitry Vyukov <dvyukov@google.com> Signed-off-by: NJiri Kosina <jkosina@suse.cz>
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