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/smb/client/fs_context.c b/fs/smb/client/fs_context.c
index 934c45ec81957f6e9086157d7beb494b1edefc20..f8bc1da3003781d962fc3c4c010b0b9dea8f0fd4 100644 (file)
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -1280,11 +1280,11 @@ 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;