cifs: Fix integer overflow while processing closetimeo mount option

JIRA: https://issues.redhat.com/browse/RHEL-87906
CVE: CVE-2025-21962

commit d5a30fd
Author: Murad Masimov <m.masimov@mt-integration.ru>
Date:   Tue Mar 11 17:22:06 2025 +0300

    cifs: Fix integer overflow while processing closetimeo mount option

    User-provided mount parameter closetimeo of type u32 is intended to have
    an upper limit, but before it is validated, the value is converted from
    seconds to jiffies which can lead to an integer overflow.

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

    Fixes: 5efdd91 ("smb3: allow deferred close timeout to be configurable")
    Signed-off-by: Murad Masimov <m.masimov@mt-integration.ru>
    Signed-off-by: Steve French <stfrench@microsoft.com>

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

Author: CKI Backport Bot

fs/smb/client/fs_context.c

@@ -1312,11 +1312,11 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
 		ctx->acdirmax = ctx->acregmax = HZ * result.uint_32;
 		break;
 	case Opt_closetimeo:
-		ctx->closetimeo = HZ * result.uint_32;
-		if (ctx->closetimeo > SMB3_MAX_DCLOSETIMEO) {
+		if (result.uint_32 > SMB3_MAX_DCLOSETIMEO / HZ) {
 			cifs_errorf(fc, "closetimeo too large\n");
 			goto cifs_parse_mount_err;
 		}
+		ctx->closetimeo = HZ * result.uint_32;
 		break;
 	case Opt_echo_interval:
 		ctx->echo_interval = result.uint_32;