On Sat, Oct 30, 2010 at 16:33 +0200, Eric Dumazet wrote:
> Le samedi 30 octobre 2010 à 18:26 +0400, Vasiliy Kulikov a écrit :
> > Structure cmsghdr is copied to userland with padding bytes
> > unitialized on architectures where __kernel_size_t is unsigned long.
> > It leads to leaking of contents of kernel stack memory.
> >
> > Signed-off-by: Vasiliy Kulikov <segooon@xxxxxxxxx>
> > ---
> > Compile tested.
> >
> > net/core/scm.c | 1 +
> > 1 files changed, 1 insertions(+), 0 deletions(-)
> >
> > diff --git a/net/core/scm.c b/net/core/scm.c
> > index 413cab8..a4a9b70 100644
> > --- a/net/core/scm.c
> > +++ b/net/core/scm.c
> > @@ -233,6 +233,7 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
> > msg->msg_flags |= MSG_CTRUNC;
> > cmlen = msg->msg_controllen;
> > }
> > + memset(&cmhdr, 0, sizeof(cmhdr));
> > cmhdr.cmsg_level = level;
> > cmhdr.cmsg_type = type;
> > cmhdr.cmsg_len = cmlen;
>
>
> ???
>
> struct cmsghdr {
> __kernel_size_t cmsg_len; /* data byte count, including hdr */
> int cmsg_level; /* originating protocol */
> int cmsg_type; /* protocol-specific type */
> };
>
> Could you explain where are the padding bytes ?
Ah, sorry, nowhere :) int is stored quite OK after long. Please ignore this patch.
Thanks,
--
Vasiliy
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