[PATCH] media: meson: vdec: Fix a NULL pointer dereference in amvdec_add_ts()

In amvdec_add_ts(), there is a dereference of kzalloc(), which could lead
to a NULL pointer dereference on failure of kzalloc().

I fix this bug by adding a NULL check of new_ts.

This bug was found by a static analyzer. The analysis employs
differential checking to identify inconsistent security operations
(e.g., checks or kfrees) between two code paths and confirms that the
inconsistent operations are not recovered in the current function or
the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

Builds with CONFIG_VIDEO_MESON_VDEC=m show no new warnings,
and our static analyzer no longer warns about this code.

Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance")
Signed-off-by: Zhou Qingyang <redacted>
---
 drivers/staging/media/meson/vdec/vdec_helpers.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.c b/drivers/staging/media/meson/vdec/vdec_helpers.c
index b9125c295d1d..41297c2f8f9a 100644
--- a/drivers/staging/media/meson/vdec/vdec_helpers.c
+++ b/drivers/staging/media/meson/vdec/vdec_helpers.c

@@ -234,6 +234,11 @@ void amvdec_add_ts(struct amvdec_session *sess, u64 ts,
 	unsigned long flags;
 
 	new_ts = kzalloc(sizeof(*new_ts), GFP_KERNEL);
+	if (!new_ts) {
+		dev_err(sess->core->dev_dec,
+			"No enough memory in %s\n", __func__);
+		return;
+	}
 	new_ts->ts = ts;
 	new_ts->tc = tc;
 	new_ts->offset = offset;

-- 
2.25.1


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On Wed, Dec 01, 2021 at 12:12:23AM +0800, Zhou Qingyang wrote:

Please run checkpatch.pl on your patches.  The dev_err() message should
be deleted because kzalloc() already has a better message built in.

WARNING: Possible unnecessary 'out of memory' message
#50: FILE: drivers/staging/media/meson/vdec/vdec_helpers.c:238:
+       if (!new_ts) {
+               dev_err(sess->core->dev_dec,

regards,
dan carpenter


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In amvdec_add_ts(), there is a dereference of kzalloc(), which could lead
to a NULL pointer dereference on failure of kzalloc().

I fix this bug by adding a NULL check of new_ts.

This bug was found by a static analyzer. The analysis employs
differential checking to identify inconsistent security operations
(e.g., checks or kfrees) between two code paths and confirms that the
inconsistent operations are not recovered in the current function or
the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

Builds with CONFIG_VIDEO_MESON_VDEC=m show no new warnings,
and our static analyzer no longer warns about this code.

Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance")
Signed-off-by: Zhou Qingyang <redacted>
---
Changes in v2:
  -  Delete dev_err() message

 drivers/staging/media/meson/vdec/vdec_helpers.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.c b/drivers/staging/media/meson/vdec/vdec_helpers.c
index b9125c295d1d..ac60514c475b 100644
--- a/drivers/staging/media/meson/vdec/vdec_helpers.c
+++ b/drivers/staging/media/meson/vdec/vdec_helpers.c

@@ -234,6 +234,9 @@ void amvdec_add_ts(struct amvdec_session *sess, u64 ts,
 	unsigned long flags;
 
 	new_ts = kzalloc(sizeof(*new_ts), GFP_KERNEL);
+	if (!new_ts)
+		return;
+
 	new_ts->ts = ts;
 	new_ts->tc = tc;
 	new_ts->offset = offset;

-- 
2.25.1


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On Fri, Dec 03, 2021 at 12:03:57AM +0800, Zhou Qingyang wrote:

In amvdec_add_ts(), there is a dereference of kzalloc(), which could lead
to a NULL pointer dereference on failure of kzalloc().

I fix this bug by adding a NULL check of new_ts.

This bug was found by a static analyzer. The analysis employs
differential checking to identify inconsistent security operations
(e.g., checks or kfrees) between two code paths and confirms that the
inconsistent operations are not recovered in the current function or
the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

Builds with CONFIG_VIDEO_MESON_VDEC=m show no new warnings,
and our static analyzer no longer warns about this code.

Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance")
Signed-off-by: Zhou Qingyang <redacted>
---

  ^^^
Thanks.  Next time put the meta commentary about how the bug was found
and the QC process under the the --- cut off line.  We don't need to
have that drama stored in the permanent git log.

Reviewed-by: Dan Carpenter <redacted>

regards,
dan carpenter


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Em Fri,  3 Dec 2021 00:03:57 +0800
Zhou Qingyang [off-list ref] escreveu:

I don't think this change is ok. Sure, it needs to check if
kzalloc() fails, but it should return -ENOMEM and the caller
should check if it returns an error. So, I would expect
that this patch would also touch the caller function at
drivers/staging/media/meson/vdec/esparser.c.

Regards,
Mauro



Thanks,
Mauro

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On Tue, Dec 14, 2021 at 02:46:13PM +0100, Mauro Carvalho Chehab wrote:

Em Fri,  3 Dec 2021 00:03:57 +0800
Zhou Qingyang [off-list ref] escreveu:

quoted

In amvdec_add_ts(), there is a dereference of kzalloc(), which could lead
to a NULL pointer dereference on failure of kzalloc().

I fix this bug by adding a NULL check of new_ts.

This bug was found by a static analyzer. The analysis employs
differential checking to identify inconsistent security operations
(e.g., checks or kfrees) between two code paths and confirms that the
inconsistent operations are not recovered in the current function or
the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

Builds with CONFIG_VIDEO_MESON_VDEC=m show no new warnings,
and our static analyzer no longer warns about this code.

Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance")
Signed-off-by: Zhou Qingyang <redacted>
---
Changes in v2:
  -  Delete dev_err() message

 drivers/staging/media/meson/vdec/vdec_helpers.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.c b/drivers/staging/media/meson/vdec/vdec_helpers.c
index b9125c295d1d..ac60514c475b 100644
--- a/drivers/staging/media/meson/vdec/vdec_helpers.c
+++ b/drivers/staging/media/meson/vdec/vdec_helpers.c

@@ -234,6 +234,9 @@ void amvdec_add_ts(struct amvdec_session *sess, u64 ts,
 	unsigned long flags;
 
 	new_ts = kzalloc(sizeof(*new_ts), GFP_KERNEL);
+	if (!new_ts)
+		return;
+
 	new_ts->ts = ts;
 	new_ts->tc = tc;
 	new_ts->offset = offset;

I don't think this change is ok. Sure, it needs to check if
kzalloc() fails, but it should return -ENOMEM and the caller
should check if it returns an error. So, I would expect
that this patch would also touch the caller function at
drivers/staging/media/meson/vdec/esparser.c.

This is why umn.edu emails still are in my black-hole :(

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In amvdec_add_ts(), there is a dereference of kzalloc(), which could lead
to a NULL pointer dereference on failure of kzalloc().

Fix this bug by adding a NULL check of new_ts.

This bug was found by a static analyzer[1].

Builds with CONFIG_VIDEO_MESON_VDEC=m show no new warnings,
and our static analyzer no longer warns about this code.

Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance")
Signed-off-by: Zhou Qingyang <redacted>
---

[1] The analysis employs differential checking to identify inconsistent
security operations (e.g., checks or kfrees) between two code paths and
confirms that the inconsistent operations are not recovered in the 
current function or the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

Changes in v3:
  -  Change the description of patch
  -  Turn the return type from 'void' to 'int'
  -  Check the return value in the caller 'esparser_queue()'

Changes in v2:
  -  Delete dev_err() 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..095100a50da8 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 b9125c295d1d..06fd66539797 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


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Zhou Qingyang, this is exactly the patch Neil wrote, except you just stuck your
name on it. Not nice.

Neil, can you post your patch with your own Signed-off-by, then I'll take that one.

Regards,

	Hans

On 15/12/2021 04:35, Zhou Qingyang wrote:

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