diff --git a/fs/smb/client/cifsacl.c b/fs/smb/client/cifsacl.c
index 3e96e151df35..c5e47a835f99 100644
--- a/fs/smb/client/cifsacl.c
+++ b/fs/smb/client/cifsacl.c
@@ -1096,13 +1096,13 @@ unsigned int setup_special_user_owner_ACE(struct smb_ace *pntace)
 static void populate_new_aces(char *nacl_base,
 		struct smb_sid *pownersid,
 		struct smb_sid *pgrpsid,
-		__u64 *pnmode, u16 *pnum_aces, u16 *pnsize,
+		__u64 *pnmode, u16 *pnum_aces, u32 *pnsize,
 		bool modefromsid,
 		bool posix)
 {
 	__u64 nmode;
 	u16 num_aces = 0;
-	u16 nsize = 0;
+	u32 nsize = 0;
 	__u64 user_mode;
 	__u64 group_mode;
 	__u64 other_mode;
@@ -1201,17 +1201,17 @@ static void populate_new_aces(char *nacl_base,
 	*pnsize = nsize;
 }
 
-static __u16 replace_sids_and_copy_aces(struct smb_acl *pdacl, struct smb_acl *pndacl,
-		struct smb_sid *pownersid, struct smb_sid *pgrpsid,
-		struct smb_sid *pnownersid, struct smb_sid *pngrpsid,
-		int *aclflag)
+static int replace_sids_and_copy_aces(struct smb_acl *pdacl, struct smb_acl *pndacl,
+				      struct smb_sid *pownersid, struct smb_sid *pgrpsid,
+				      struct smb_sid *pnownersid, struct smb_sid *pngrpsid,
+				      int *aclflag, u16 *pnsize)
 {
 	int i;
 	u16 size = 0;
 	struct smb_ace *pntace = NULL;
 	char *acl_base = NULL;
 	u16 src_num_aces = 0;
-	u16 nsize = 0;
+	u32 nsize = 0;
 	struct smb_ace *pnntace = NULL;
 	char *nacl_base = NULL;
 	u16 ace_size = 0;
@@ -1240,9 +1240,12 @@ static __u16 replace_sids_and_copy_aces(struct smb_acl *pdacl, struct smb_acl *p
 
 		size += le16_to_cpu(pntace->size);
 		nsize += ace_size;
+		if (nsize > U16_MAX)
+			return -EOVERFLOW;
 	}
 
-	return nsize;
+	*pnsize = nsize;
+	return 0;
 }
 
 static int set_chmod_dacl(struct smb_acl *pdacl, struct smb_acl *pndacl,
@@ -1254,7 +1257,7 @@ static int set_chmod_dacl(struct smb_acl *pdacl, struct smb_acl *pndacl,
 	struct smb_ace *pntace = NULL;
 	char *acl_base = NULL;
 	u16 src_num_aces = 0;
-	u16 nsize = 0;
+	u32 nsize = 0;
 	struct smb_ace *pnntace = NULL;
 	char *nacl_base = NULL;
 	u16 num_aces = 0;
@@ -1305,6 +1308,8 @@ static int set_chmod_dacl(struct smb_acl *pdacl, struct smb_acl *pndacl,
 
 		nsize += cifs_copy_ace(pnntace, pntace, NULL);
 		num_aces++;
+		if (nsize > U16_MAX)
+			return -EOVERFLOW;
 
 next_ace:
 		size += le16_to_cpu(pntace->size);
@@ -1321,6 +1326,10 @@ static int set_chmod_dacl(struct smb_acl *pdacl, struct smb_acl *pndacl,
 	}
 
 finalize_dacl:
+	/* The DACL size field is 16-bit on the wire, see MS-DTYP 2.4.5 */
+	if (nsize > U16_MAX)
+		return -EOVERFLOW;
+
 	pndacl->num_aces = cpu_to_le16(num_aces);
 	pndacl->size = cpu_to_le16(nsize);
 
@@ -1473,6 +1482,8 @@ static int build_sec_desc(struct smb_ntsd *pntsd, struct smb_ntsd *pnntsd,
 
 		rc = set_chmod_dacl(dacl_ptr, ndacl_ptr, owner_sid_ptr, group_sid_ptr,
 				    pnmode, mode_from_sid, posix);
+		if (rc)
+			return rc;
 
 		sidsoffset = ndacloffset + le16_to_cpu(ndacl_ptr->size);
 		/* copy the non-dacl portion of secdesc */
@@ -1548,10 +1559,12 @@ static int build_sec_desc(struct smb_ntsd *pntsd, struct smb_ntsd *pnntsd,
 
 		if (dacloffset) {
 			/* Replace ACEs for old owner with new one */
-			size = replace_sids_and_copy_aces(dacl_ptr, ndacl_ptr,
-					owner_sid_ptr, group_sid_ptr,
-					nowner_sid_ptr, ngroup_sid_ptr,
-					aclflag);
+			rc = replace_sids_and_copy_aces(dacl_ptr, ndacl_ptr,
+							owner_sid_ptr, group_sid_ptr,
+							nowner_sid_ptr, ngroup_sid_ptr,
+							aclflag, &size);
+			if (rc)
+				goto chown_chgrp_exit;
 			ndacl_ptr->size = cpu_to_le16(size);
 		}