linux-kernel - Re: [PATCH] net: core: scm: fix information leak to userland

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 30 Oct 2010 16:33:25 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Vasiliy Kulikov <segooon@...il.com>
Cc:	kernel-janitors@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Tejun Heo <tj@...nel.org>,
	"Serge E. Hallyn" <serge@...lyn.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: core: scm: fix information leak to userland

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@...il.com>
> ---
>  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 ?



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/