[PATCH][CIFS] Fix uninitialized pointer access to dacl_ptr in build_sec_desc

[Steve French <smfrench@gmail.com>]

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    smb3: fix possible access to uninitialized pointer to DACL

    dacl_ptr can be null so we must check for it (ie if dacloffset is
set) everywhere dacl_ptr is
    used in build_sec_desc - and we were missing one check

    Addresses-Coverity: 1475598 ("Explicit null dereference")


-- 
Thanks,

Steve

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From ec06cb04376e5abc927a9b85dd768ce8728965bb Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Tue, 22 Jun 2021 17:54:50 -0500
Subject: [PATCH] smb3: fix possible access to uninitialized pointer to DACL

dacl_ptr can be null so we must check for it everywhere it is
used in build_sec_desc.

Addresses-Coverity: 1475598 ("Explicit null dereference")
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifsacl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index 784407f9280f..25a8139336fa 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -1308,7 +1308,7 @@ static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
 		ndacl_ptr = (struct cifs_acl *)((char *)pnntsd + ndacloffset);
 		ndacl_ptr->revision =
 			dacloffset ? dacl_ptr->revision : cpu_to_le16(ACL_REVISION);
-		ndacl_ptr->num_aces = dacl_ptr->num_aces;
+		ndacl_ptr->num_aces = dacloffset ? dacl_ptr->num_aces : 0;
 
 		if (uid_valid(uid)) { /* chown */
 			uid_t id;
-- 
2.30.2