Re: [PATCH] cifs: fix possible memory corruption in CIFSFindNext

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merged

On Tue, Aug 23, 2011 at 6:21 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> The name_len variable in CIFSFindNext is a signed int that gets set to
> the resume_name_len in the cifs_search_info. The resume_name_len however
> is unsigned and for some infolevels is populated directly from a 32 bit
> value sent by the server.
>
> If the server sends a very large value for this, then that value could
> look negative when converted to a signed int. That would make that
> value pass the PATH_MAX check later in CIFSFindNext. The name_len would
> then be used as a length value for a memcpy. It would then be treated
> as unsigned again, and the memcpy scribbles over a ton of memory.
>
> Fix this by making the name_len an unsigned value in CIFSFindNext.
>
> Cc: <stable@xxxxxxxxxx>
> Reported-by: Darren Lavender <dcl@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
>  fs/cifs/cifssmb.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> index f4d0988..950464d 100644
> --- a/fs/cifs/cifssmb.c
> +++ b/fs/cifs/cifssmb.c
> @@ -4089,7 +4089,8 @@ int CIFSFindNext(const int xid, struct cifs_tcon *tcon,
>        T2_FNEXT_RSP_PARMS *parms;
>        char *response_data;
>        int rc = 0;
> -       int bytes_returned, name_len;
> +       int bytes_returned;
> +       unsigned int name_len;
>        __u16 params, byte_count;
>
>        cFYI(1, "In FindNext");
> --
> 1.7.6
>
>



-- 
Thanks,

Steve
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