linux-kernel - Re: [4.2.0-rc1-00201-g59c3cb5] Regression: kernel NULL pointer dereference

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:	Sun, 12 Jul 2015 09:52:51 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Jörg Otte <jrg.otte@...il.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>
Cc:	David Airlie <airlied@...ux.ie>,
	DRI <dri-devel@...ts.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Subject: Re: [4.2.0-rc1-00201-g59c3cb5] Regression: kernel NULL pointer dereference

On Sun, Jul 12, 2015 at 1:03 AM, Jörg Otte <jrg.otte@...il.com> wrote:
>
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000009
> IP: [<ffffffffbd3447bb>] 0xffffffffbd3447bb

Ugh. Please enable KALLSYMS to get sane symbols.

But yes, "crtc_state->base.active" is at offset 9 from "crtc_state",
so it's pretty clearly just that change frm

-       if (intel_crtc->active) {
+       if (crtc_state->base.active) {

and "crtc_state" is NULL.

And the code very much knows that crtc_state can be NULL, since it's
initialized with

        crtc_state = state->base.state ?
                intel_atomic_get_crtc_state(state->base.state,
intel_crtc) : NULL;

Tssk. Daniel? Should I just revert that commit dec4f799d0a4
("drm/i915: Use crtc_state->active in primary check_plane func") for
now, or is there a better fix? Like just checking crtc_state for NULL?

                    Linus
--
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/