[PATCH AUTOSEL 5.18 35/39] smb3: check xattr value length earlier

Sasha Levin
2022-08-14T16:33:45Z

From: Steve French <stfrench@microsoft.com>

[ Upstream commit 5fa2cffba0b82336a2244d941322eb1627ff787b ]

Coverity complains about assigning a pointer based on
value length before checking that value length goes
beyond the end of the SMB. Although this is even more
unlikely as value length is a single byte, and the
pointer is not dereferenced until laterm, it is clearer
to check the lengths first.

Addresses-Coverity: 1467704 ("Speculative execution data leak")
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/smb2ops.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 19f957785a73..a09563efe78a 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -1120,9 +1120,7 @@ move_smb2_ea_to_cifs(char *dst, size_t dst_size,
size_t name_len, value_len, user_name_len;

while (src_size > 0) {
- name = &src->ea_data[0];
name_len = (size_t)src->ea_name_length;
- value = &src->ea_data[src->ea_name_length + 1];
value_len = (size_t)le16_to_cpu(src->ea_value_length);

if (name_len == 0)
@@ -1134,6 +1132,9 @@ move_smb2_ea_to_cifs(char *dst, size_t dst_size,
goto out;
}

+ name = &src->ea_data[0];
+ value = &src->ea_data[src->ea_name_length + 1];
+
if (ea_name) {
if (ea_name_len == name_len &&
memcmp(ea_name, name, name_len) == 0) {
--
2.35.1