linux-kernel - [PATCH 5.13 256/800] smb3: fix possible access to uninitialized pointer to DACL

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Date:   Mon, 12 Jul 2021 08:04:39 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Steve French <stfrench@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.13 256/800] smb3: fix possible access to uninitialized pointer to DACL

From: Steve French <stfrench@...rosoft.com>

[ Upstream commit a5628263a9f8d47d9a1548fe9d5d75ba4423a735 ]

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@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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..a18dee071fcd 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 = dacl_ptr ? dacl_ptr->num_aces : 0;
 
 		if (uid_valid(uid)) { /* chown */
 			uid_t id;
-- 
2.30.2