linux-kernel - [PATCH 4/4] cifs: Fix integer overflow while processing closetimeo mount option

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Message-ID: <20250311142206.2045-5-m.masimov@mt-integration.ru>
Date: Tue, 11 Mar 2025 17:22:06 +0300
From: Murad Masimov <m.masimov@...integration.ru>
To: Steve French <sfrench@...ba.org>
CC: Paulo Alcantara <pc@...guebit.com>, Ronnie Sahlberg
	<ronniesahlberg@...il.com>, Shyam Prasad N <sprasad@...rosoft.com>, Tom
 Talpey <tom@...pey.com>, Bharath SM <bharathsm@...rosoft.com>, Jeff Layton
	<jlayton@...nel.org>, Suresh Jayaraman <sjayaraman@...e.de>, "Paulo Alcantara
 (SUSE)" <pc@....nz>, <linux-cifs@...r.kernel.org>,
	<samba-technical@...ts.samba.org>, <linux-kernel@...r.kernel.org>,
	<lvc-project@...uxtesting.org>, Murad Masimov <m.masimov@...integration.ru>
Subject: [PATCH 4/4] 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: 5efdd9122eff ("smb3: allow deferred close timeout to be configurable")
Signed-off-by: Murad Masimov <m.masimov@...integration.ru>
---
 fs/smb/client/fs_context.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
index 89e54cf238f8..da5973c228ed 100644
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -1366,11 +1366,11 @@ 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;
--
2.39.2