cifs: Fix integer overflow while processing actimeo mount option

[ Upstream commit 64f690ee22c99e16084e0e45181b2a1eed2fa149 ]

User-provided mount parameter actimeo 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: 6d20e8406f09 ("cifs: add attribute cache timeout (actimeo) tunable")
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 9b1c0e0dfc63b6b91e25eb85d991bcd61675538a..f45a29a51700b1b8f5c1d17911dd731cf25e5e70 100644 (file)
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -1069,7 +1069,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
                ctx->acdirmax = HZ * result.uint_32;
                break;
        case Opt_actimeo:
-               if (HZ * result.uint_32 > CIFS_MAX_ACTIMEO) {
+               if (result.uint_32 > CIFS_MAX_ACTIMEO / HZ) {
                        cifs_errorf(fc, "timeout too large\n");
                        goto cifs_parse_mount_err;
                }