2021-06-21 21:46:08

by Kees Cook

Subject: [PATCH] cifs: Avoid field over-reading memcpy()

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally reading across neighboring fields.

Instead of using memcpy to read across multiple struct members, just
perform per-member assignments as already done for other members.

Signed-off-by: Kees Cook <[email protected]>
---
fs/cifs/smb2pdu.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 31784e3fa96f..962826dc3316 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2892,7 +2892,10 @@ SMB2_open(const unsigned int xid, struct cifs_open_parms *oparms, __le16 *path,
#endif /* CIFS_DEBUG2 */

if (buf) {
- memcpy(buf, &rsp->CreationTime, 32);
+ buf->CreationTime = rsp->CreationTime;
+ buf->LastAccessTime = rsp->LastAccessTime;
+ buf->LastWriteTime = rsp->LastWriteTime;
+ buf->ChangeTime = rsp->ChangeTime;
buf->AllocationSize = rsp->AllocationSize;
buf->EndOfFile = rsp->EndofFile;
buf->Attributes = rsp->FileAttributes;
--
2.30.2

2021-06-22 02:43:44

by Steve French

Subject: Re: [PATCH] cifs: Avoid field over-reading memcpy()

merged into cifs-2.6.git for-next

On Mon, Jun 21, 2021 at 4:45 PM Kees Cook <[email protected]> wrote:
>
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memcpy(), memmove(), and memset(), avoid
> intentionally reading across neighboring fields.
>
> Instead of using memcpy to read across multiple struct members, just
> perform per-member assignments as already done for other members.
>
> Signed-off-by: Kees Cook <[email protected]>
> ---
> fs/cifs/smb2pdu.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
> index 31784e3fa96f..962826dc3316 100644
> --- a/fs/cifs/smb2pdu.c
> +++ b/fs/cifs/smb2pdu.c
> @@ -2892,7 +2892,10 @@ SMB2_open(const unsigned int xid, struct cifs_open_parms *oparms, __le16 *path,
> #endif /* CIFS_DEBUG2 */
>
> if (buf) {
> - memcpy(buf, &rsp->CreationTime, 32);
> + buf->CreationTime = rsp->CreationTime;
> + buf->LastAccessTime = rsp->LastAccessTime;
> + buf->LastWriteTime = rsp->LastWriteTime;
> + buf->ChangeTime = rsp->ChangeTime;
> buf->AllocationSize = rsp->AllocationSize;
> buf->EndOfFile = rsp->EndofFile;
> buf->Attributes = rsp->FileAttributes;
> --
> 2.30.2
>


--
Thanks,

Steve