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: stable@xxxxxxxxxxxxxxx
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Reported-by: Adam G. Metzler <adamgmetzler@xxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/cifs/readdir.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index 5de03ec..a090bbe 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -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;
}
--
1.7.6.4
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