linux-kernel - [PATCH AUTOSEL 6.6 020/294] cifs: add validation check for the fields in smb

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Message-Id: <20250505225634.2688578-20-sashal@kernel.org>
Date: Mon,  5 May 2025 18:52:00 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Namjae Jeon <linkinjeon@...nel.org>,
	Steve French <stfrench@...rosoft.com>,
	Sasha Levin <sashal@...nel.org>,
	sfrench@...ba.org,
	linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org
Subject: [PATCH AUTOSEL 6.6 020/294] cifs: add validation check for the fields in smb_aces

From: Namjae Jeon <linkinjeon@...nel.org>

[ Upstream commit eeb827f2922eb07ffbf7d53569cc95b38272646f ]

cifs.ko is missing validation check when accessing smb_aces.
This patch add validation check for the fields in smb_aces.

Signed-off-by: Namjae Jeon <linkinjeon@...nel.org>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/smb/client/cifsacl.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/fs/smb/client/cifsacl.c b/fs/smb/client/cifsacl.c
index db9076da2182a..bf32bc22ebd69 100644
--- a/fs/smb/client/cifsacl.c
+++ b/fs/smb/client/cifsacl.c
@@ -811,7 +811,23 @@ static void parse_dacl(struct smb_acl *pdacl, char *end_of_acl,
 			return;
 
 		for (i = 0; i < num_aces; ++i) {
+			if (end_of_acl - acl_base < acl_size)
+				break;
+
 			ppace[i] = (struct smb_ace *) (acl_base + acl_size);
+			acl_base = (char *)ppace[i];
+			acl_size = offsetof(struct smb_ace, sid) +
+				offsetof(struct smb_sid, sub_auth);
+
+			if (end_of_acl - acl_base < acl_size ||
+			    ppace[i]->sid.num_subauth == 0 ||
+			    ppace[i]->sid.num_subauth > SID_MAX_SUB_AUTHORITIES ||
+			    (end_of_acl - acl_base <
+			     acl_size + sizeof(__le32) * ppace[i]->sid.num_subauth) ||
+			    (le16_to_cpu(ppace[i]->size) <
+			     acl_size + sizeof(__le32) * ppace[i]->sid.num_subauth))
+				break;
+
 #ifdef CONFIG_CIFS_DEBUG2
 			dump_ace(ppace[i], end_of_acl);
 #endif
@@ -855,7 +871,6 @@ static void parse_dacl(struct smb_acl *pdacl, char *end_of_acl,
 				(void *)ppace[i],
 				sizeof(struct smb_ace)); */
 
-			acl_base = (char *)ppace[i];
 			acl_size = le16_to_cpu(ppace[i]->size);
 		}
 
-- 
2.39.5