From nobody Fri Sep 25 04:41:49 2026 Received: from cstnet.cn (smtp25.cstnet.cn [159.226.251.25]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C28E73C5540; Wed, 16 Sep 2026 17:23:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.25 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789579431; cv=none; b=nrERR5jJH9geisnmv/ZTHUP8H5dJkoxDA0XrFM2wv8+tQJrEJqgi7281ZUInpi8Scgt9ASNIoWOilYd/KZFt3CQ0aG+1LjHRvxJ6/lbLF7BskSEkHnLSQ6OAYP3IdJc5m8yOzKFlxEqaA9qqNXRxc/aUKS60enxnlrHkPWyNjvA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789579431; c=relaxed/simple; bh=i/9Nz5U0exD65WjNlUWRI5iAClBZ5byKB6pnI1UoGUk=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=WFrw1LW0HQ4CXbOhzfYAom5lQfwDUHwC9wWESGGbz6rbabvq5sdAR8Mj69AtoaAwKPxn20Mzi/m6/OyVwy62lDbGVdI95ZGeTUZM6LirEoA+C0bOa9s/Jbh5tnOvwVZVZ/3yw2xwoRfATKiPiaRpDiWceiHAU4Ne7G3pjfdtB4k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.25 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from dfae2b116770.home.arpa (unknown [36.110.52.2]) by APP-05 (Coremail) with SMTP id zQCowACnETyc0KpqD4xuCA--.45751S2; Thu, 17 Sep 2026 01:23:40 +0800 (CST) From: Wentao Liang To: airlied@gmail.com Cc: chris@chris-wilson.co.uk, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, linux-kernel@vger.kernel.org, rodrigo.vivi@intel.com, simona@ffwll.ch, tursulin@ursulin.net, Wentao Liang , stable@vger.kernel.org Subject: [PATCH] drm/i915/gt: Fix ce use-after-free in signal_irq_work() Date: Wed, 16 Sep 2026 17:23:12 +0000 Message-Id: <20260916172312.2087555-1-vulab@iscas.ac.cn> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: zQCowACnETyc0KpqD4xuCA--.45751S2 X-Coremail-Antispam: 1UD129KBjvJXoW7ZF4fGF13Jr1rurWktrW5Wrg_yoW8Zry5pr 43JFyayrZ5XFsxuan8C3W0vF1aga4xtF18Wan5Gw1xAwn0q3Z5J34Sya4jyFyY9r4kXr1Y qrWqqa4xGF4UZr7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9q14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26ryj6F1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AKxV WxJr0_GcWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2Wl Yx0E2Ix0cI8IcVAFwI0_Jw0_WrylYx0Ex4A2jsIE14v26r4j6F4UMcvjeVCFs4IE7xkEbV WUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7Cj xVA2Y2ka0xkIwI1lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4I kC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWU WwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_JF I_Gr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1lIxAIcVCF04k26cxKx2IYs7xG 6r1j6r1xMIIF0xvEx4A2jsIE14v26r4j6F4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr1j6F 4UJbIYCTnIWIevJa73UjIFyTuYvjfU5byZUUUUU X-CM-SenderInfo: pyxotu46lvutnvoduhdfq/1tbiBgUMA2qqok9p+gADsx Content-Type: text/plain; charset="utf-8" The final intel_context_put() may drop the last reference to a signaler context. GuC parallel child contexts are freed immediately by __guc_context_destroy() rather than via call_rcu(), so reading ce->signal_link.next to advance the RCU iterator afterwards is a use-after-free. Cache the next context before the loop body instead. Fixes: c744d50363b7 ("drm/i915/gt: Split the breadcrumb spinlock between gl= obal and contexts") Cc: stable@vger.kernel.org Signed-off-by: Wentao Liang --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/= i915/gt/intel_breadcrumbs.c index c10ac0ab3bfa..f840e98792cd 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -174,7 +174,7 @@ static void signal_irq_work(struct irq_work *work) struct intel_breadcrumbs *b =3D container_of(work, typeof(*b), irq_work); const ktime_t timestamp =3D ktime_get(); struct llist_node *signal, *sn; - struct intel_context *ce; + struct intel_context *ce, *cn; =20 signal =3D NULL; if (unlikely(!llist_empty(&b->signaled_requests))) @@ -210,9 +210,19 @@ static void signal_irq_work(struct irq_work *work) =20 rcu_read_lock(); atomic_inc(&b->signaler_active); - list_for_each_entry_rcu(ce, &b->signalers, signal_link) { + for (ce =3D list_first_or_null_rcu(&b->signalers, typeof(*ce), signal_lin= k); + ce; + ce =3D cn) { struct i915_request *rq; =20 + /* + * Grab the next signaler up front, as dropping the final + * reference below may free the current one before we + * advance the iterator. + */ + cn =3D list_next_or_null_rcu(&b->signalers, &ce->signal_link, + typeof(*cn), signal_link); + list_for_each_entry_rcu(rq, &ce->signals, signal_link) { bool release; =20 --=20 2.34.1