From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 73095CFD2F6 for ; Thu, 27 Nov 2025 16:08:44 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D9A9B10E087; Thu, 27 Nov 2025 16:08:43 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="Z7MhA283"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id 785D710E109 for ; Thu, 27 Nov 2025 16:08:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1764259721; bh=fKB78e3lsISybq6xiwMBy2evTO5QQdBxRjQx5Vhczbs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Z7MhA283kW1kWrisAQVBYbAqR/L1cA0VY98cM0dfM172qy/Q2uP8Wns4vqPoob3ci kdA26FGtNBUK4INp0oS2yJ6MIGBn5wjuMaEaLfJxoOHfWHsZDeEYhScGwz6OuZ4o7p 41k9npqjqIfr9sU533loCbDfv+MvbNDv+3GVCkYyXYaNSj56d5DY5hcJDenIlq6nRd q78OHkET6QYeao7XlmL0ETnLY9ea11Q40iJl37H/33gfz6NQz7ys+JIJ6WRqD74VIW PlxRcOB8QJ4eWkgJJq6diw6qbJFb2hm0TofPinj2GXBBhKRFKMMBYI7LCJuBXIpsE+ TyHs+L+NWmUtw== Received: from fedora (unknown [IPv6:2a01:e0a:2c:6930:d919:a6e:5ea1:8a9f]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id 8831017E1122; Thu, 27 Nov 2025 17:08:40 +0100 (CET) Date: Thu, 27 Nov 2025 17:08:36 +0100 From: Boris Brezillon To: Steven Price Cc: Akash Goel , liviu.dudau@arm.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, daniel@ffwll.ch, nd@arm.com Subject: Re: [PATCH] drm/panthor: Prevent potential UAF in group creation Message-ID: <20251127170836.0921f02e@fedora> In-Reply-To: References: <20251127081239.3744766-1-akash.goel@arm.com> Organization: Collabora X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Thu, 27 Nov 2025 16:02:15 +0000 Steven Price wrote: > On 27/11/2025 08:12, Akash Goel wrote: > > This commit prevents the possibility of a use after free issue in the > > GROUP_CREATE ioctl function, which arose as pointer to the group is > > accessed in that ioctl function after storing it in the Xarray. > > A malicious userspace can second guess the handle of a group and try > > to call GROUP_DESTROY ioctl from another thread around the same time > > as GROUP_CREATE ioctl. > > > > To prevent the use after free exploit, this commit uses a mark on an > > entry of group pool Xarray which is added just before returning from > > the GROUP_CREATE ioctl function. The mark is checked for all ioctls > > that specify the group handle and so userspace won't be abe to delete > > a group that isn't marked yet. > > > > Co-developed-by: Boris Brezillon > > Signed-off-by: Akash Goel > > Reviewed-by: Steven Price > > I *think* this should have a... > > Fixes: d2624d90a0b7 ("drm/panthor: assign unique names to queues") > > ... as I don't believe it was a problem before the rearrangement that > happened there. Oh, yeah, I didn't notice the commit was missing a Fixes tag, and you're correct about the offending commit. > > Thanks, > Steve > > > --- > > drivers/gpu/drm/panthor/panthor_sched.c | 19 +++++++++++++++---- > > 1 file changed, 15 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c > > index b834123a6560..a6b8024e1a3c 100644 > > --- a/drivers/gpu/drm/panthor/panthor_sched.c > > +++ b/drivers/gpu/drm/panthor/panthor_sched.c > > @@ -779,6 +779,12 @@ struct panthor_job_profiling_data { > > */ > > #define MAX_GROUPS_PER_POOL 128 > > > > +/* > > + * Mark added on an entry of group pool Xarray to identify if the group has > > + * been fully initialized and can be accessed elsewhere in the driver code. > > + */ > > +#define GROUP_REGISTERED XA_MARK_1 > > + > > /** > > * struct panthor_group_pool - Group pool > > * > > @@ -3007,7 +3013,7 @@ void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile) > > return; > > > > xa_lock(&gpool->xa); > > - xa_for_each(&gpool->xa, i, group) { > > + xa_for_each_marked(&gpool->xa, i, group, GROUP_REGISTERED) { > > guard(spinlock)(&group->fdinfo.lock); > > pfile->stats.cycles += group->fdinfo.data.cycles; > > pfile->stats.time += group->fdinfo.data.time; > > @@ -3727,6 +3733,8 @@ int panthor_group_create(struct panthor_file *pfile, > > > > group_init_task_info(group); > > > > + xa_set_mark(&gpool->xa, gid, GROUP_REGISTERED); > > + > > return gid; > > > > err_erase_gid: > > @@ -3744,6 +3752,9 @@ int panthor_group_destroy(struct panthor_file *pfile, u32 group_handle) > > struct panthor_scheduler *sched = ptdev->scheduler; > > struct panthor_group *group; > > > > + if (!xa_get_mark(&gpool->xa, group_handle, GROUP_REGISTERED)) > > + return -EINVAL; > > + > > group = xa_erase(&gpool->xa, group_handle); > > if (!group) > > return -EINVAL; > > @@ -3769,12 +3780,12 @@ int panthor_group_destroy(struct panthor_file *pfile, u32 group_handle) > > } > > > > static struct panthor_group *group_from_handle(struct panthor_group_pool *pool, > > - u32 group_handle) > > + unsigned long group_handle) > > { > > struct panthor_group *group; > > > > xa_lock(&pool->xa); > > - group = group_get(xa_load(&pool->xa, group_handle)); > > + group = group_get(xa_find(&pool->xa, &group_handle, group_handle, GROUP_REGISTERED)); > > xa_unlock(&pool->xa); > > > > return group; > > @@ -3861,7 +3872,7 @@ panthor_fdinfo_gather_group_mem_info(struct panthor_file *pfile, > > return; > > > > xa_lock(&gpool->xa); > > - xa_for_each(&gpool->xa, i, group) { > > + xa_for_each_marked(&gpool->xa, i, group, GROUP_REGISTERED) { > > stats->resident += group->fdinfo.kbo_sizes; > > if (group->csg_id >= 0) > > stats->active += group->fdinfo.kbo_sizes; >