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SubjectRE: [RFC][PATCH 3/3] audit: Audit proc cmdline value
Date


-----Original Message-----
From: Mateusz Guzik [mailto:mguzik@redhat.com]
Sent: Monday, January 06, 2014 9:09 AM
To: William Roberts
Cc: linux-audit@redhat.com; linux-mm@kvack.org; linux-kernel@vger.kernel.org; rgb@redhat.com; viro@zeniv.linux.org.uk; akpm@linux-foundation.org; sds@tycho.nsa.gov; William Roberts
Subject: Re: [RFC][PATCH 3/3] audit: Audit proc cmdline value

I can't comment on the concept, but have one nit.

On Mon, Jan 06, 2014 at 07:30:30AM -0800, William Roberts wrote:
> +static void audit_log_cmdline(struct audit_buffer *ab, struct task_struct *tsk,
> + struct audit_context *context)
> +{
> + int res;
> + char *buf;
> + char *msg = "(null)";
> + audit_log_format(ab, " cmdline=");
> +
> + /* Not cached */
> + if (!context->cmdline) {
> + buf = kmalloc(PATH_MAX, GFP_KERNEL);
> + if (!buf)
> + goto out;
> + res = get_cmdline(tsk, buf, PATH_MAX);
> + /* Ensure NULL terminated */
> + if (buf[res-1] != '\0')
> + buf[res-1] = '\0';

This accesses memory below the buffer if get_cmdline returned 0, which I believe will be the case when someone jokingly unmaps the area (all maybe when it is swapped out but can't be swapped in due to I/O errors).
[William Roberts]
Sorry for the weird inline posting (Thanks MS Outlook of doom). Anyways, this isn’t a nit. This is a major issue that should be dealt with. Thanks.

Also since you are just putting 0 in there anyway I don't see much point in testing for it.

> + context->cmdline = buf;
> + }
> + msg = context->cmdline;
> +out:
> + audit_log_untrustedstring(ab, msg);
> +}
> +



--
Mateusz Guzik
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