fs/ntfs3: Prevent integer overflow in hdr_first_de()

[ Upstream commit 6bb81b94f7a9cba6bde9a905cef52a65317a8b04 ]

The "de_off" and "used" variables come from the disk so they both need to
check.  The problem is that on 32bit systems if they're both greater than
UINT_MAX - 16 then the check does work as intended because of an integer
overflow.

Fixes: 60ce8dfde035 ("fs/ntfs3: Fix wrong if in hdr_first_de")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/ntfs3/ntfs.h b/fs/ntfs3/ntfs.h
index 964e27c7b901647c75313ee05b95fe2b725cfbff..c1d1c4a7cf4d6036e7dccb99f8ae134ebd7803cc 100644 (file)
--- a/fs/ntfs3/ntfs.h
+++ b/fs/ntfs3/ntfs.h
@@ -717,7 +717,7 @@ static inline struct NTFS_DE *hdr_first_de(const struct INDEX_HDR *hdr)
        struct NTFS_DE *e;
        u16 esize;
 
-       if (de_off >= used || de_off + sizeof(struct NTFS_DE) > used )
+       if (de_off >= used || size_add(de_off, sizeof(struct NTFS_DE)) > used)
                return NULL;
 
        e = Add2Ptr(hdr, de_off);