[PATCH] media: iris: fix use-after-free of fmt_src during MBPF check

[Vishnu Reddy]

A race condition was observed during concurrency testing. the core MBPF
check walks the list of active instances and reads fields such as fmt_src
height and width. At the same time, iris_close() could free these format
structures before the instance was removed from core list. this creates a
use-after-free window where the MBPF checker access the freed memory and
read invalid values.

To fix this, the freeing of fmt_src and fmt_dst is moved to the end
of iris_close(), after the instance has been removed from the core
list and teardown is complete. This avoids accessing dangling pointers
during the MBPF check.

Signed-off-by: Vishnu Reddy <busanna.reddy@xxxxxxxxxxxxxxxx>
---
 drivers/media/platform/qcom/iris/iris_vdec.c | 6 ------
 drivers/media/platform/qcom/iris/iris_vdec.h | 1 -
 drivers/media/platform/qcom/iris/iris_venc.c | 6 ------
 drivers/media/platform/qcom/iris/iris_venc.h | 1 -
 drivers/media/platform/qcom/iris/iris_vidc.c | 6 ++----
 5 files changed, 2 insertions(+), 18 deletions(-)

diff --git a/drivers/media/platform/qcom/iris/iris_vdec.c b/drivers/media/platform/qcom/iris/iris_vdec.c
index 719217399a30..99d544e2af4f 100644
--- a/drivers/media/platform/qcom/iris/iris_vdec.c
+++ b/drivers/media/platform/qcom/iris/iris_vdec.c
@@ -61,12 +61,6 @@ int iris_vdec_inst_init(struct iris_inst *inst)
 	return iris_ctrls_init(inst);
 }
 
-void iris_vdec_inst_deinit(struct iris_inst *inst)
-{
-	kfree(inst->fmt_dst);
-	kfree(inst->fmt_src);
-}
-
 static const struct iris_fmt iris_vdec_formats_cap[] = {
 	[IRIS_FMT_NV12] = {
 		.pixfmt = V4L2_PIX_FMT_NV12,
diff --git a/drivers/media/platform/qcom/iris/iris_vdec.h b/drivers/media/platform/qcom/iris/iris_vdec.h
index ec1ce55d1375..5123d2a340e1 100644
--- a/drivers/media/platform/qcom/iris/iris_vdec.h
+++ b/drivers/media/platform/qcom/iris/iris_vdec.h
@@ -9,7 +9,6 @@
 struct iris_inst;
 
 int iris_vdec_inst_init(struct iris_inst *inst);
-void iris_vdec_inst_deinit(struct iris_inst *inst);
 int iris_vdec_enum_fmt(struct iris_inst *inst, struct v4l2_fmtdesc *f);
 int iris_vdec_try_fmt(struct iris_inst *inst, struct v4l2_format *f);
 int iris_vdec_s_fmt(struct iris_inst *inst, struct v4l2_format *f);
diff --git a/drivers/media/platform/qcom/iris/iris_venc.c b/drivers/media/platform/qcom/iris/iris_venc.c
index aa27b22704eb..4d886769d958 100644
--- a/drivers/media/platform/qcom/iris/iris_venc.c
+++ b/drivers/media/platform/qcom/iris/iris_venc.c
@@ -79,12 +79,6 @@ int iris_venc_inst_init(struct iris_inst *inst)
 	return iris_ctrls_init(inst);
 }
 
-void iris_venc_inst_deinit(struct iris_inst *inst)
-{
-	kfree(inst->fmt_dst);
-	kfree(inst->fmt_src);
-}
-
 static const struct iris_fmt iris_venc_formats_cap[] = {
 	[IRIS_FMT_H264] = {
 		.pixfmt = V4L2_PIX_FMT_H264,
diff --git a/drivers/media/platform/qcom/iris/iris_venc.h b/drivers/media/platform/qcom/iris/iris_venc.h
index c4db7433da53..00c1716b2747 100644
--- a/drivers/media/platform/qcom/iris/iris_venc.h
+++ b/drivers/media/platform/qcom/iris/iris_venc.h
@@ -9,7 +9,6 @@
 struct iris_inst;
 
 int iris_venc_inst_init(struct iris_inst *inst);
-void iris_venc_inst_deinit(struct iris_inst *inst);
 int iris_venc_enum_fmt(struct iris_inst *inst, struct v4l2_fmtdesc *f);
 int iris_venc_try_fmt(struct iris_inst *inst, struct v4l2_format *f);
 int iris_venc_s_fmt(struct iris_inst *inst, struct v4l2_format *f);
diff --git a/drivers/media/platform/qcom/iris/iris_vidc.c b/drivers/media/platform/qcom/iris/iris_vidc.c
index bd38d84c9cc7..5eb1786b0737 100644
--- a/drivers/media/platform/qcom/iris/iris_vidc.c
+++ b/drivers/media/platform/qcom/iris/iris_vidc.c
@@ -289,10 +289,6 @@ int iris_close(struct file *filp)
 	v4l2_m2m_ctx_release(inst->m2m_ctx);
 	v4l2_m2m_release(inst->m2m_dev);
 	mutex_lock(&inst->lock);
-	if (inst->domain == DECODER)
-		iris_vdec_inst_deinit(inst);
-	else if (inst->domain == ENCODER)
-		iris_venc_inst_deinit(inst);
 	iris_session_close(inst);
 	iris_inst_change_state(inst, IRIS_INST_DEINIT);
 	iris_v4l2_fh_deinit(inst, filp);
@@ -304,6 +300,8 @@ int iris_close(struct file *filp)
 	mutex_unlock(&inst->lock);
 	mutex_destroy(&inst->ctx_q_lock);
 	mutex_destroy(&inst->lock);
+	kfree(inst->fmt_src);
+	kfree(inst->fmt_dst);
 	kfree(inst);
 
 	return 0;

---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20260226-fix-use-after-free-of-fmt_src-during-mbpf-abc27f573400

Best regards,
-- 
Vishnu Reddy <busanna.reddy@xxxxxxxxxxxxxxxx>