Commit 7023676f authored Dec 01, 2011 by Jeff Layton Committed by Steve French Dec 08, 2011

cifs: check for NULL last_entry before calling cifs_save_resume_key

Prior to commit eaf35b1e, 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 eaf35b1e, 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: stable@vger.kernel.org
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>

parent 95edcff4

fs/cifs/readdir.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -554,7 +554,10 @@ static int find_cifs_entry(const int xid, struct cifs_tcon *pTcon,
		rc);
		return rc;
		}
		cifs_save_resume_key(cifsFile->srch_inf.last_entry, cifsFile);
		/* FindFirst/Next set last_entry to NULL on malformed reply */
		if (cifsFile->srch_inf.last_entry)
		cifs_save_resume_key(cifsFile->srch_inf.last_entry,
		cifsFile);
		}

		while ((index_to_find >= cifsFile->srch_inf.index_of_last_entry) &&
		@@ -562,7 +565,10 @@ static int find_cifs_entry(const int xid, struct cifs_tcon *pTcon,
		cFYI(1, "calling findnext2");
		rc = CIFSFindNext(xid, pTcon, cifsFile->netfid,
		&cifsFile->srch_inf);
		cifs_save_resume_key(cifsFile->srch_inf.last_entry, cifsFile);
		/* FindFirst/Next set last_entry to NULL on malformed reply */
		if (cifsFile->srch_inf.last_entry)
		cifs_save_resume_key(cifsFile->srch_inf.last_entry,
		cifsFile);
		if (rc)
		return -ENOENT;
		}

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