[lvc-project] [PATCH 5.10] cifs: fix integer overflow in match_server()

[Roman Smirnov]

From: Roman Smirnov <r.smirnov at omp.ru>

[ Upstream commit 2510859475d7f46ed7940db0853f3342bf1b65ee ]

The echo_interval is not limited in any way during mounting,
which makes it possible to write a large number to it. This can
cause an overflow when multiplying ctx->echo_interval by HZ in
match_server().

Add constraints for echo_interval to smb3_fs_context_parse_param().

Found by Linux Verification Center (linuxtesting.org) with Svace.

Fixes: adfeb3e00e8e1 ("cifs: Make echo interval tunable")
Cc: stable at vger.kernel.org
Signed-off-by: Roman Smirnov <r.smirnov at omp.ru>
Signed-off-by: Steve French <stfrench at microsoft.com>
Signed-off-by: Roman Smirnov <r.smirnov at omp.ru>
---
 fs/cifs/connect.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index a3c0e6a4e484..322b8be73bb8 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1915,6 +1915,12 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 					 __func__);
 				goto cifs_parse_mount_err;
 			}
+			if (option < SMB_ECHO_INTERVAL_MIN ||
+			    option > SMB_ECHO_INTERVAL_MAX) {
+				cifs_dbg(VFS, "%s: Echo interval is out of bounds\n",
+					 __func__);
+				goto cifs_parse_mount_err;
+			}
 			vol->echo_interval = option;
 			break;
 		case Opt_snapshot:
-- 
2.43.0