• Linus Torvalds's avatar
    vfs: fix handling of lock allocation failure in lease-break case · 6d4b9e38
    Linus Torvalds authored
    Bruce Fields notes that commit 778fc546 ("locks: fix tracking of
    inprogress lease breaks") introduced a possible error pointer
    dereference on failure to allocate memory.  locks_conflict() will
    dereference the passed-in new lease lock structure that may be an error pointer.
    
    This means an open (without O_NONBLOCK set) on a file with a lease
    applied (generally only done when Samba or nfsd (with v4) is running)
    could crash if a kmalloc() fails.
    
    So instead of playing games with IS_ERROR() all over the place, just
    check the allocation failure early.  That makes the code more
    straightforward, and avoids this possible bad pointer dereference.
    Based-on-patch-by: default avatarJ. Bruce Fields <bfields@redhat.com>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    6d4b9e38
locks.c 58.9 KB