vfs: fix pipe counter breakage
authorAl Viro <viro@ZenIV.linux.org.uk>
Tue, 12 Mar 2013 02:59:49 +0000 (02:59 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 14 Mar 2013 18:29:51 +0000 (11:29 -0700)
commitcc6de71e8c24edbad16e45c011013d40eb903ffd
tree0679f9de7e5d8b83b8aae72cac37cc9e052f9c78
parent3126603e01babcec7cfe2f284099e2adff095bff
vfs: fix pipe counter breakage

commit a930d8790552658140d7d0d2e316af4f0d76a512 upstream.

If you open a pipe for neither read nor write, the pipe code will not
add any usage counters to the pipe, causing the 'struct pipe_inode_info"
to be potentially released early.

That doesn't normally matter, since you cannot actually use the pipe,
but the pipe release code - particularly fasync handling - still expects
the actual pipe infrastructure to all be there.  And rather than adding
NULL pointer checks, let's just disallow this case, the same way we
already do for the named pipe ("fifo") case.

This is ancient going back to pre-2.4 days, and until trinity, nobody
naver noticed.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/pipe.c