cifs: check for NULL last_entry before calling cifs_save_resume_key
authorJeff Layton <jlayton@redhat.com>
Fri, 2 Dec 2011 01:23:34 +0000 (20:23 -0500)
committerGreg Kroah-Hartman <gregkh@suse.de>
Wed, 21 Dec 2011 20:58:30 +0000 (12:58 -0800)
commit5bf4dba2647ee7eb377cb0f809d7abea461d34ae
tree66b9cbe8d211944382e5c6d48ccca4f480aa9d1d
parent42354507ebd4124dbe46e46fe1ba7d9e0af0fe70
cifs: check for NULL last_entry before calling cifs_save_resume_key

commit 7023676f9ee851d94f0942e879243fc1f9081c47 upstream.

Prior to commit eaf35b1, cifs_save_resume_key had some NULL pointer
checks at the top. It turns out that at least one of those NULL
pointer checks is needed after all.

When the LastNameOffset in a FIND reply appears to be beyond the end of
the buffer, CIFSFindFirst and CIFSFindNext will set srch_inf.last_entry
to NULL. Since eaf35b1, the code will now oops in this situation.

Fix this by having the callers check for a NULL last entry pointer
before calling cifs_save_resume_key. No change is needed for the
call site in cifs_readdir as it's not reachable with a NULL
current_entry pointer.

This should fix:

    https://bugzilla.redhat.com/show_bug.cgi?id=750247

Cc: Christoph Hellwig <hch@infradead.org>
Reported-by: Adam G. Metzler <adamgmetzler@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
fs/cifs/readdir.c