[PATCH AUTOSEL 4.20 62/77] cifs: fix memory leak of an allocated cifs_ntsd structure

From: Sasha Levin
Date: Thu Feb 14 2019 - 21:10:41 EST

From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

[ Upstream commit 73aaf920cc72024c4a4460cfa46d56e5014172f3 ]

The call to SMB2_queary_acl can allocate memory to pntsd and also
return a failure via a call to SMB2_query_acl (and then query_info).
This occurs when query_info allocates the structure and then in
query_info the call to smb2_validate_and_copy_iov fails. Currently the
failure just returns without kfree'ing pntsd hence causing a memory

Currently, *data is allocated if it's not already pointing to a buffer,
so it needs to be kfree'd only if was allocated in query_info, so the
fix adds an allocated flag to track this. Also set *dlen to zero on
an error just to be safe since *data is kfree'd.

Also set errno to -ENOMEM if the allocation of *data fails.

Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Reviewed-by: Dan Carpener <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
fs/cifs/smb2pdu.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index c393ac255af7..d1ae7cdb236d 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2714,6 +2714,7 @@ query_info(const unsigned int xid, struct cifs_tcon *tcon,
int resp_buftype = CIFS_NO_BUFFER;
struct cifs_ses *ses = tcon->ses;
int flags = 0;
+ bool allocated = false;

cifs_dbg(FYI, "Query Info\n");

@@ -2753,14 +2754,21 @@ query_info(const unsigned int xid, struct cifs_tcon *tcon,
"Error %d allocating memory for acl\n",
*dlen = 0;
+ rc = -ENOMEM;
goto qinf_exit;
+ allocated = true;

rc = smb2_validate_and_copy_iov(le16_to_cpu(rsp->OutputBufferOffset),
&rsp_iov, min_len, *data);
+ if (rc && allocated) {
+ kfree(*data);
+ *data = NULL;
+ *dlen = 0;
+ }