ksmbd: fix heap-based overflow in set_ntacl_dacl()

The testcase use SMB2_SET_INFO_HE command to set a malformed file attribute
under the label `security.NTACL`. SMB2_QUERY_INFO_HE command in testcase
trigger the following overflow.

[ 4712.003781] ==================================================================
[ 4712.003790] BUG: KASAN: slab-out-of-bounds in build_sec_desc+0x842/0x1dd0 [ksmbd]
[ 4712.003807] Write of size 1060 at addr ffff88801e34c068 by task kworker/0:0/4190

[ 4712.003813] CPU: 0 PID: 4190 Comm: kworker/0:0 Not tainted 5.19.0-rc5 #1
[ 4712.003850] Workqueue: ksmbd-io handle_ksmbd_work [ksmbd]
[ 4712.003867] Call Trace:
[ 4712.003870]  <TASK>
[ 4712.003873]  dump_stack_lvl+0x49/0x5f
[ 4712.003935]  print_report.cold+0x5e/0x5cf
[ 4712.003972]  ? ksmbd_vfs_get_sd_xattr+0x16d/0x500 [ksmbd]
[ 4712.003984]  ? cmp_map_id+0x200/0x200
[ 4712.003988]  ? build_sec_desc+0x842/0x1dd0 [ksmbd]
[ 4712.004000]  kasan_report+0xaa/0x120
[ 4712.004045]  ? build_sec_desc+0x842/0x1dd0 [ksmbd]
[ 4712.004056]  kasan_check_range+0x100/0x1e0
[ 4712.004060]  memcpy+0x3c/0x60
[ 4712.004064]  build_sec_desc+0x842/0x1dd0 [ksmbd]
[ 4712.004076]  ? parse_sec_desc+0x580/0x580 [ksmbd]
[ 4712.004088]  ? ksmbd_acls_fattr+0x281/0x410 [ksmbd]
[ 4712.004099]  smb2_query_info+0xa8f/0x6110 [ksmbd]
[ 4712.004111]  ? psi_group_change+0x856/0xd70
[ 4712.004148]  ? update_load_avg+0x1c3/0x1af0
[ 4712.004152]  ? asym_cpu_capacity_scan+0x5d0/0x5d0
[ 4712.004157]  ? xas_load+0x23/0x300
[ 4712.004162]  ? smb2_query_dir+0x1530/0x1530 [ksmbd]
[ 4712.004173]  ? _raw_spin_lock_bh+0xe0/0xe0
[ 4712.004179]  handle_ksmbd_work+0x30e/0x1020 [ksmbd]
[ 4712.004192]  process_one_work+0x778/0x11c0
[ 4712.004227]  ? _raw_spin_lock_irq+0x8e/0xe0
[ 4712.004231]  worker_thread+0x544/0x1180
[ 4712.004234]  ? __cpuidle_text_end+0x4/0x4
[ 4712.004239]  kthread+0x282/0x320
[ 4712.004243]  ? process_one_work+0x11c0/0x11c0
[ 4712.004246]  ? kthread_complete_and_exit+0x30/0x30
[ 4712.004282]  ret_from_fork+0x1f/0x30

This patch add the buffer validation for security descriptor that is
stored by malformed SMB2_SET_INFO_HE command. and allocate large
response buffer about SMB2_O_INFO_SECURITY file info class.

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-17771
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 25 insertions, 14 deletions

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 5943cb17a9b0..9751cc92c111 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -535,9 +535,10 @@ int smb2_allocate_rsp_buf(struct ksmbd_work *work)
 		struct smb2_query_info_req *req;
 
 		req = smb2_get_msg(work->request_buf);
-		if (req->InfoType == SMB2_O_INFO_FILE &&
-		    (req->FileInfoClass == FILE_FULL_EA_INFORMATION ||
-		     req->FileInfoClass == FILE_ALL_INFORMATION))
+		if ((req->InfoType == SMB2_O_INFO_FILE &&
+		     (req->FileInfoClass == FILE_FULL_EA_INFORMATION ||
+		     req->FileInfoClass == FILE_ALL_INFORMATION)) ||
+		    req->InfoType == SMB2_O_INFO_SECURITY)
 			sz = large_sz;
 	}
 
@@ -2988,7 +2989,7 @@ int smb2_open(struct ksmbd_work *work)
 						goto err_out;
 
 					rc = build_sec_desc(user_ns,
-							    pntsd, NULL,
+							    pntsd, NULL, 0,
 							    OWNER_SECINFO |
 							    GROUP_SECINFO |
 							    DACL_SECINFO,
@@ -3833,6 +3834,15 @@ static int verify_info_level(int info_level)
 	return 0;
 }
 
+static int smb2_resp_buf_len(struct ksmbd_work *work, unsigned short hdr2_len)
+{
+	int free_len;
+
+	free_len = (int)(work->response_sz -
+		(get_rfc1002_len(work->response_buf) + 4)) - hdr2_len;
+	return free_len;
+}
+
 static int smb2_calc_max_out_buf_len(struct ksmbd_work *work,
 				     unsigned short hdr2_len,
 				     unsigned int out_buf_len)
@@ -3842,9 +3852,7 @@ static int smb2_calc_max_out_buf_len(struct ksmbd_work *work,
 	if (out_buf_len > work->conn->vals->max_trans_size)
 		return -EINVAL;
 
-	free_len = (int)(work->response_sz -
-			 (get_rfc1002_len(work->response_buf) + 4)) -
-		hdr2_len;
+	free_len = smb2_resp_buf_len(work, hdr2_len);
 	if (free_len < 0)
 		return -EINVAL;
 
@@ -5107,10 +5115,10 @@ static int smb2_get_info_sec(struct ksmbd_work *work,
 	struct smb_ntsd *pntsd = (struct smb_ntsd *)rsp->Buffer, *ppntsd = NULL;
 	struct smb_fattr fattr = {{0}};
 	struct inode *inode;
-	__u32 secdesclen;
+	__u32 secdesclen = 0;
 	unsigned int id = KSMBD_NO_FID, pid = KSMBD_NO_FID;
 	int addition_info = le32_to_cpu(req->AdditionalInformation);
-	int rc;
+	int rc = 0, ppntsd_size = 0;
 
 	if (addition_info & ~(OWNER_SECINFO | GROUP_SECINFO | DACL_SECINFO |
 			      PROTECTED_DACL_SECINFO |
@@ -5156,11 +5164,14 @@ static int smb2_get_info_sec(struct ksmbd_work *work,
 
 	if (test_share_config_flag(work->tcon->share_conf,
 				   KSMBD_SHARE_FLAG_ACL_XATTR))
-		ksmbd_vfs_get_sd_xattr(work->conn, user_ns,
-				       fp->filp->f_path.dentry, &ppntsd);
-
-	rc = build_sec_desc(user_ns, pntsd, ppntsd, addition_info,
-			    &secdesclen, &fattr);
+		ppntsd_size = ksmbd_vfs_get_sd_xattr(work->conn, user_ns,
+						     fp->filp->f_path.dentry,
+						     &ppntsd);
+
+	/* Check if sd buffer size exceeds response buffer size */
+	if (smb2_resp_buf_len(work, 8) > ppntsd_size)
+		rc = build_sec_desc(user_ns, pntsd, ppntsd, ppntsd_size,
+				    addition_info, &secdesclen, &fattr);
 	posix_acl_release(fattr.cf_acls);
 	posix_acl_release(fattr.cf_dacls);
 	kfree(ppntsd);