From: Anand Moon <linux.amoon@gmail•com>
To: Neil Armstrong <neil.armstrong@linaro•org>,
Maarten Lankhorst <maarten.lankhorst@linux•intel.com>,
Maxime Ripard <mripard@kernel•org>,
Thomas Zimmermann <tzimmermann@suse•de>,
David Airlie <airlied@gmail•com>, Simona Vetter <simona@ffwll•ch>,
Kevin Hilman <khilman@baylibre•com>,
Jerome Brunet <jbrunet@baylibre•com>,
Martin Blumenstingl <martin.blumenstingl@googlemail•com>,
Mauro Carvalho Chehab <mchehab@kernel•org>,
Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
Maxime Jourdan <mjourdan@baylibre•com>,
Hans Verkuil <hverkuil@kernel•org>,
dri-devel@lists•freedesktop.org (open list:DRM DRIVERS FOR
AMLOGIC SOCS),
linux-amlogic@lists•infradead.org (open list:DRM DRIVERS FOR
AMLOGIC SOCS),
linux-arm-kernel@lists•infradead.org (moderated list:ARM/Amlogic
Meson SoC support), linux-kernel@vger•kernel.org (open list),
linux-media@vger•kernel.org (open list:MESON VIDEO DECODER
DRIVER FOR AMLOGIC SOCS),
linux-staging@lists•linux.dev (open list:STAGING SUBSYSTEM)
Cc: Sashiko <sashiko-bot@kernel•org>,
Nicolas Dufresne <nicolas@ndufresne•ca>
Subject: [PATCH v6 7/8] media: meson: vdec: Fix NULL pointer dereference in ISR handlers
Date: Sat, 30 May 2026 15:12:53 +0530 [thread overview]
Message-ID: <20260530094326.11892-8-linux.amoon@gmail.com> (raw)
In-Reply-To: <20260530094326.11892-1-linux.amoon@gmail.com>
The hard interrupt handler (vdec_isr) and the threaded interrupt handler
(vdec_threaded_isr) directly read core->cur_sess without synchronization
or validation. If a streaming teardown concurrently clears core->cur_sess
to NULL while an interrupt is being processed, a NULL pointer dereference
occurs when accessing the session fields or codec operations.
Fix this race condition by using READ_ONCE() to obtain a stable, atomic
snapshot of core->cur_sess. Check if the returned session pointer is NULL,
and return IRQ_NONE immediately if the session has already been torn down.
Cc: Nicolas Dufresne <nicolas@ndufresne•ca>
Reported-by: Sashiko <sashiko-bot@kernel•org>
Closes: https://lore.kernel.org/all/20260521090944.F35401F00A3D@smtp.kernel.org/
Fixes: 3e7f51bd9607 ("media: meson: add v4l2 m2m video decoder driver")
Signed-off-by: Anand Moon <linux.amoon@gmail•com>
---
drivers/staging/media/meson/vdec/vdec.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c
index f99335effe17..3897c75b19c8 100644
--- a/drivers/staging/media/meson/vdec/vdec.c
+++ b/drivers/staging/media/meson/vdec/vdec.c
@@ -996,17 +996,36 @@ static const struct v4l2_file_operations vdec_fops = {
static irqreturn_t vdec_isr(int irq, void *data)
{
struct amvdec_core *core = data;
- struct amvdec_session *sess = core->cur_sess;
+ struct amvdec_session *sess;
+ irqreturn_t ret = IRQ_HANDLED;
+
+ /*
+ * Use READ_ONCE to secure an atomic snapshot of the pointer,
+ * protecting against concurrent clearing during streaming
+ * teardowns.
+ */
+ sess = READ_ONCE(core->cur_sess);
+ if (!sess)
+ return IRQ_NONE;
sess->last_irq_jiffies = get_jiffies_64();
+ ret = sess->fmt_out->codec_ops->isr(sess);
- return sess->fmt_out->codec_ops->isr(sess);
+ return ret;
}
static irqreturn_t vdec_threaded_isr(int irq, void *data)
{
struct amvdec_core *core = data;
- struct amvdec_session *sess = core->cur_sess;
+ struct amvdec_session *sess;
+
+ /*
+ * Prevent late-stage threaded interrupts from dereferencing a NULL
+ * session.
+ */
+ sess = READ_ONCE(core->cur_sess);
+ if (!sess)
+ return IRQ_NONE;
return sess->fmt_out->codec_ops->threaded_isr(sess);
}
--
2.50.1
next prev parent reply other threads:[~2026-05-30 9:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-30 9:42 [PATCH v6 0/8] media: meson: Fix memory leak in error path in vdec Anand Moon
2026-05-30 9:42 ` [PATCH v6 1/8] media: meson: vdec: Fix memory leaks and lifetime of m2m device Anand Moon
2026-05-30 9:42 ` [PATCH v6 2/8] media: meson: vdec: Fix concurrent STREAMON / STREAMOFF race conditions Anand Moon
2026-05-30 9:42 ` [PATCH v6 3/8] media: meson: vdec: Handle kthread failure and free codec state Anand Moon
2026-05-30 9:42 ` [PATCH v6 4/8] media: meson: vdec: Condition buffer flushing on queue type in start_streaming Anand Moon
2026-05-30 9:42 ` [PATCH v6 5/8] media: meson: vdec: Cancel esparser work during teardown Anand Moon
2026-05-30 9:42 ` [PATCH v6 6/8] media: meson: vdec: Configure DMA mask and segment size in probe Anand Moon
2026-05-30 9:42 ` Anand Moon [this message]
2026-05-30 9:42 ` [PATCH v6 8/8] gpu: drm: meson: Fix DMA max segment size for DMABUF imports Anand Moon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260530094326.11892-8-linux.amoon@gmail.com \
--to=linux.amoon@gmail$(echo .)com \
--cc=airlied@gmail$(echo .)com \
--cc=dri-devel@lists$(echo .)freedesktop.org \
--cc=gregkh@linuxfoundation$(echo .)org \
--cc=hverkuil@kernel$(echo .)org \
--cc=jbrunet@baylibre$(echo .)com \
--cc=khilman@baylibre$(echo .)com \
--cc=linux-amlogic@lists$(echo .)infradead.org \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linux-media@vger$(echo .)kernel.org \
--cc=linux-staging@lists$(echo .)linux.dev \
--cc=maarten.lankhorst@linux$(echo .)intel.com \
--cc=martin.blumenstingl@googlemail$(echo .)com \
--cc=mchehab@kernel$(echo .)org \
--cc=mjourdan@baylibre$(echo .)com \
--cc=mripard@kernel$(echo .)org \
--cc=neil.armstrong@linaro$(echo .)org \
--cc=nicolas@ndufresne$(echo .)ca \
--cc=sashiko-bot@kernel$(echo .)org \
--cc=simona@ffwll$(echo .)ch \
--cc=tzimmermann@suse$(echo .)de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox