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 C0D78CFD2F6 for ; Thu, 27 Nov 2025 16:52:52 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2B2C210E831; Thu, 27 Nov 2025 16:52:52 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="WD7Gcdvp"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id 21D8910E831 for ; Thu, 27 Nov 2025 16:52:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1764262369; bh=9Wk/LOORMxz5YmWzkq/tH6kFDa3gDiX1h7VECY5oaHY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=WD7GcdvphRIsxYuP0hAcKS5ZqW7up3VgoS/84uXoCsc/2tuQUR2KL0qMmgQpDQ8Ib cz91cNz9IpmmKElkOgeMGYSpAK4oXCSa3T3p3AAXt/8tGrbKQv7XXD2bHP5MJ4Gw/a 3vrLNVI48V+I1HXRu2qe9n3FpjP1t2lwBFlxZxeikrwzQVpagZWGrfgQVBIapM5nSD 2uJrildBBIE5urINQNe5w4B6Kh+xw0d/I/OLhSl9l5njJUJa4NWw2Y9UoesCCHZm+C BLfJ57aExa5MF86bTqGn0KH+EIkmUEFMjHKFOjNsdWRhBD72J8zFYqholbtHyR+FOL Rv9rew3dgfqSw== 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 3A7A717E1122; Thu, 27 Nov 2025 17:52:49 +0100 (CET) Date: Thu, 27 Nov 2025 17:52:47 +0100 From: Boris Brezillon To: Akash Goel Cc: liviu.dudau@arm.com, steven.price@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 v2] drm/panthor: Prevent potential UAF in group creation Message-ID: <20251127175247.2d64d82e@fedora> In-Reply-To: <20251127164912.3788155-1-akash.goel@arm.com> References: <20251127164912.3788155-1-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 16:49:12 +0000 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. > > v2: Add R-bs and fixes tags > > Fixes: de85488138247 ("drm/panthor: Add the scheduler logical block") > Co-developed-by: Boris Brezillon Signed-off-by: Boris Brezillon to please checkpacth. > Signed-off-by: Akash Goel > Reviewed-by: Boris Brezillon > Reviewed-by: Steven Price > --- > 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;