cifs: Fix integer overflow while processing closetimeo mount option

[ Upstream commit d5a30fddfe2f2e540f6c43b59cf701809995faef ]

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@mt-integration.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
index f45a29a51700b1b8f5c1d17911dd731cf25e5e70..24c42043a227183c0eff349fad29780727650cac 100644 (file)
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -1081,11 +1081,11 @@ 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;