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From: Mansur Alisha Shaik <>
	Mansur Alisha Shaik <>
Subject: [PATCH v2 1/3] venus: core: handle race condititon for core ops
Date: Thu, 10 Sep 2020 18:14:14 +0530	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

For core ops we are having only write protect but there
is no read protect, because of this in multthreading
and concurrency, one CPU core is reading without wait
which is causing the NULL pointer dereferece crash.

one such scenario is as show below, where in one CPU
core, core->ops becoming NULL and in another CPU core
calling core->ops->session_init().

CPU: core-7:
Call trace:
 hfi_session_init+0x180/0x1dc [venus_core]
 vdec_queue_setup+0x9c/0x364 [venus_dec]
 vb2_core_reqbufs+0x1e4/0x368 [videobuf2_common]
 vb2_reqbufs+0x4c/0x64 [videobuf2_v4l2]
 v4l2_m2m_reqbufs+0x50/0x84 [v4l2_mem2mem]
 v4l2_m2m_ioctl_reqbufs+0x2c/0x38 [v4l2_mem2mem]

CPU: core-0:
Call trace:
 venus_shutdown+0x98/0xfc [venus_core]
 venus_sys_error_handler+0x64/0x148 [venus_core]

Signed-off-by: Mansur Alisha Shaik <>
Acked-by: Stanimir Varbanov <>
Changes in V2:
- Addressed review comments by stan by validating on top
- of

 drivers/media/platform/qcom/venus/hfi.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c
index a59022a..3137071 100644
--- a/drivers/media/platform/qcom/venus/hfi.c
+++ b/drivers/media/platform/qcom/venus/hfi.c
@@ -195,7 +195,7 @@ EXPORT_SYMBOL_GPL(hfi_session_create);
 int hfi_session_init(struct venus_inst *inst, u32 pixfmt)
 	struct venus_core *core = inst->core;
-	const struct hfi_ops *ops = core->ops;
+	const struct hfi_ops *ops;
 	int ret;
 	if (inst->state != INST_UNINIT)
@@ -204,10 +204,13 @@ int hfi_session_init(struct venus_inst *inst, u32 pixfmt)
 	inst->hfi_codec = to_codec_type(pixfmt);
+	mutex_lock(&core->lock);
+	ops = core->ops;
 	ret = ops->session_init(inst, inst->session_type, inst->hfi_codec);
 	if (ret)
 		return ret;
+	mutex_unlock(&core->lock);
 	ret = wait_session_msg(inst);
 	if (ret)
 		return ret;
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member 
of Code Aurora Forum, hosted by The Linux Foundation

  reply	other threads:[~2020-09-10 12:47 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-10 12:44 [PATCH v2 0/3] Venus - Handle race conditions in concurrency Mansur Alisha Shaik
2020-09-10 12:44 ` Mansur Alisha Shaik [this message]
2020-09-11 10:10   ` [PATCH v2 1/3] venus: core: handle race condititon for core ops Stanimir Varbanov
2020-09-17  1:51     ` mansur
2020-09-10 12:44 ` [PATCH v2 2/3] venus: core: cancel pending work items in workqueue Mansur Alisha Shaik
2020-09-11 10:22   ` Stanimir Varbanov
2020-09-17  1:53     ` mansur
2020-09-10 12:44 ` [PATCH v2 3/3] venus: handle use after free for iommu_map/iommu_unmap Mansur Alisha Shaik

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