linux-kernel - [PATCH v3] media: meson: vdec: potential dereference of null pointer

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Message-Id: <20220113065928.1198125-1-jiasheng@iscas.ac.cn>
Date:   Thu, 13 Jan 2022 14:59:28 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     hverkuil-cisco@...all.nl, narmstrong@...libre.com,
        mchehab@...nel.org, gregkh@...uxfoundation.org,
        khilman@...libre.com, jbrunet@...libre.com,
        martin.blumenstingl@...glemail.com, p.zabel@...gutronix.de
Cc:     linux-media@...r.kernel.org, linux-amlogic@...ts.infradead.org,
        linux-staging@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH v3] media: meson: vdec: potential dereference of null pointer

As the possible failure of the kzalloc(), the 'new_ts' could be NULL
pointer.
Therefore, it should be better to check it in order to avoid the
dereference of the NULL pointer.
Also, the caller esparser_queue() needs to deal with the return value of
the amvdec_add_ts().

Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance")
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
Changelog

v1 -> v2

* Change 1. Change the return type of amvdec_add_ts from void to int.
* Change 2. Return -ENOMEN if alloc fail and return 0 if not.
* Change 3. Modify the caller to deal with the error.

v2 -> v3

* Change 1. Fix the indentation and refine the commit message.
---
 drivers/staging/media/meson/vdec/esparser.c     | 7 ++++++-
 drivers/staging/media/meson/vdec/vdec_helpers.c | 8 ++++++--
 drivers/staging/media/meson/vdec/vdec_helpers.h | 4 ++--
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/media/meson/vdec/esparser.c b/drivers/staging/media/meson/vdec/esparser.c
index db7022707ff8..86ccc8937afc 100644
--- a/drivers/staging/media/meson/vdec/esparser.c
+++ b/drivers/staging/media/meson/vdec/esparser.c
@@ -328,7 +328,12 @@ esparser_queue(struct amvdec_session *sess, struct vb2_v4l2_buffer *vbuf)
 
 	offset = esparser_get_offset(sess);
 
-	amvdec_add_ts(sess, vb->timestamp, vbuf->timecode, offset, vbuf->flags);
+	ret = amvdec_add_ts(sess, vb->timestamp, vbuf->timecode, offset, vbuf->flags);
+	if (ret) {
+		v4l2_m2m_buf_done(vbuf, VB2_BUF_STATE_ERROR);
+		return ret;
+	}
+
 	dev_dbg(core->dev, "esparser: ts = %llu pld_size = %u offset = %08X flags = %08X\n",
 		vb->timestamp, payload_size, offset, vbuf->flags);
 
diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.c b/drivers/staging/media/meson/vdec/vdec_helpers.c
index 203d7afa085d..7d2a75653250 100644
--- a/drivers/staging/media/meson/vdec/vdec_helpers.c
+++ b/drivers/staging/media/meson/vdec/vdec_helpers.c
@@ -227,13 +227,16 @@ int amvdec_set_canvases(struct amvdec_session *sess,
 }
 EXPORT_SYMBOL_GPL(amvdec_set_canvases);
 
-void amvdec_add_ts(struct amvdec_session *sess, u64 ts,
-		   struct v4l2_timecode tc, u32 offset, u32 vbuf_flags)
+int amvdec_add_ts(struct amvdec_session *sess, u64 ts,
+		  struct v4l2_timecode tc, u32 offset, u32 vbuf_flags)
 {
 	struct amvdec_timestamp *new_ts;
 	unsigned long flags;
 
 	new_ts = kzalloc(sizeof(*new_ts), GFP_KERNEL);
+	if (!new_ts)
+		return -ENOMEM;
+
 	new_ts->ts = ts;
 	new_ts->tc = tc;
 	new_ts->offset = offset;
@@ -242,6 +245,7 @@ void amvdec_add_ts(struct amvdec_session *sess, u64 ts,
 	spin_lock_irqsave(&sess->ts_spinlock, flags);
 	list_add_tail(&new_ts->list, &sess->timestamps);
 	spin_unlock_irqrestore(&sess->ts_spinlock, flags);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(amvdec_add_ts);
 
diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.h b/drivers/staging/media/meson/vdec/vdec_helpers.h
index 88137d15aa3a..4bf3e61d081b 100644
--- a/drivers/staging/media/meson/vdec/vdec_helpers.h
+++ b/drivers/staging/media/meson/vdec/vdec_helpers.h
@@ -56,8 +56,8 @@ void amvdec_dst_buf_done_offset(struct amvdec_session *sess,
  * @offset: offset in the VIFIFO where the associated packet was written
  * @flags: the vb2_v4l2_buffer flags
  */
-void amvdec_add_ts(struct amvdec_session *sess, u64 ts,
-		   struct v4l2_timecode tc, u32 offset, u32 flags);
+int amvdec_add_ts(struct amvdec_session *sess, u64 ts,
+		  struct v4l2_timecode tc, u32 offset, u32 flags);
 void amvdec_remove_ts(struct amvdec_session *sess, u64 ts);
 
 /**
-- 
2.25.1