media: mtk-vpu: avoid unaligned access to DTCM buffer.
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Message ID 20200210035351.227499-1-hsinyi@chromium.org
State New
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Series
  • media: mtk-vpu: avoid unaligned access to DTCM buffer.
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Commit Message

Hsin-Yi Wang Feb. 10, 2020, 3:53 a.m. UTC
struct vpu_run *run in vpu_init_ipi_handler() is an ioremapped DTCM (Data
Tightly Coupled Memory) buffer shared with AP.  It's not able to do
unaligned access. Otherwise kernel would crash due to unable to handle
kernel paging request.

struct vpu_run {
	u32 signaled;
	char fw_ver[VPU_FW_VER_LEN];
	unsigned int	dec_capability;
	unsigned int	enc_capability;
	wait_queue_head_t wq;
};

fw_ver starts at 4 byte boundary. If system enables
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, strscpy() will do
read_word_at_a_time(), which tries to read 8-byte: *(unsigned long *)addr

Copy the string by memcpy_fromio() for this buffer to avoid unaligned
access.

Fixes: 85709cbf1524 ("media: replace strncpy() by strscpy()")
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
---
 drivers/media/platform/mtk-vpu/mtk_vpu.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Comments

Hans Verkuil Feb. 14, 2020, 10:52 a.m. UTC | #1
Hi Hsin-Yi Wang,

On 2/10/20 4:53 AM, Hsin-Yi Wang wrote:
> struct vpu_run *run in vpu_init_ipi_handler() is an ioremapped DTCM (Data
> Tightly Coupled Memory) buffer shared with AP.  It's not able to do
> unaligned access. Otherwise kernel would crash due to unable to handle
> kernel paging request.
> 
> struct vpu_run {
> 	u32 signaled;
> 	char fw_ver[VPU_FW_VER_LEN];
> 	unsigned int	dec_capability;
> 	unsigned int	enc_capability;
> 	wait_queue_head_t wq;
> };
> 
> fw_ver starts at 4 byte boundary. If system enables
> CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, strscpy() will do
> read_word_at_a_time(), which tries to read 8-byte: *(unsigned long *)addr
> 
> Copy the string by memcpy_fromio() for this buffer to avoid unaligned
> access.
> 
> Fixes: 85709cbf1524 ("media: replace strncpy() by strscpy()")
> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>

This patch results in the following sparse warnings:

sparse: WARNINGS
SPARSE:mtk-vpu/mtk_vpu.c mtk-vpu/mtk_vpu.c:834:52:  warning: incorrect type in argument 3 (incompatible argument 1 (different address spaces))
SPARSE:mtk-vpu/mtk_vpu.c mtk-vpu/mtk_vpu.c:609:29:  warning: dereference of noderef expression
SPARSE:mtk-vpu/mtk_vpu.c mtk-vpu/mtk_vpu.c:613:35:  warning: dereference of noderef expression
SPARSE:mtk-vpu/mtk_vpu.c mtk-vpu/mtk_vpu.c:614:35:  warning: dereference of noderef expression

Can you take a look?

Regards,

	Hans

> ---
>  drivers/media/platform/mtk-vpu/mtk_vpu.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/mtk-vpu/mtk_vpu.c b/drivers/media/platform/mtk-vpu/mtk_vpu.c
> index a768707abb94..e705e85d6f5a 100644
> --- a/drivers/media/platform/mtk-vpu/mtk_vpu.c
> +++ b/drivers/media/platform/mtk-vpu/mtk_vpu.c
> @@ -600,13 +600,16 @@ int vpu_load_firmware(struct platform_device *pdev)
>  }
>  EXPORT_SYMBOL_GPL(vpu_load_firmware);
>  
> -static void vpu_init_ipi_handler(void *data, unsigned int len, void *priv)
> +static void vpu_init_ipi_handler(void __iomem *data, unsigned int len,
> +				 void *priv)
>  {
>  	struct mtk_vpu *vpu = (struct mtk_vpu *)priv;
> -	struct vpu_run *run = (struct vpu_run *)data;
> +	struct vpu_run __iomem *run = data;
>  
>  	vpu->run.signaled = run->signaled;
> -	strscpy(vpu->run.fw_ver, run->fw_ver, sizeof(vpu->run.fw_ver));
> +	memcpy_fromio(vpu->run.fw_ver, run->fw_ver, sizeof(vpu->run.fw_ver));
> +	/* Make sure the string is NUL-terminated */
> +	vpu->run.fw_ver[sizeof(vpu->run.fw_ver) - 1] = '\0';
>  	vpu->run.dec_capability = run->dec_capability;
>  	vpu->run.enc_capability = run->enc_capability;
>  	wake_up_interruptible(&vpu->run.wq);
>
Hsin-Yi Wang Feb. 14, 2020, 11:59 a.m. UTC | #2
On Fri, Feb 14, 2020 at 6:52 PM Hans Verkuil <hverkuil-cisco@xs4all.nl> wrote:
>
> Hi Hsin-Yi Wang,
>
> On 2/10/20 4:53 AM, Hsin-Yi Wang wrote:
> > struct vpu_run *run in vpu_init_ipi_handler() is an ioremapped DTCM (Data
> > Tightly Coupled Memory) buffer shared with AP.  It's not able to do
> > unaligned access. Otherwise kernel would crash due to unable to handle
> > kernel paging request.
> >
> > struct vpu_run {
> >       u32 signaled;
> >       char fw_ver[VPU_FW_VER_LEN];
> >       unsigned int    dec_capability;
> >       unsigned int    enc_capability;
> >       wait_queue_head_t wq;
> > };
> >
> > fw_ver starts at 4 byte boundary. If system enables
> > CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, strscpy() will do
> > read_word_at_a_time(), which tries to read 8-byte: *(unsigned long *)addr
> >
> > Copy the string by memcpy_fromio() for this buffer to avoid unaligned
> > access.
> >
> > Fixes: 85709cbf1524 ("media: replace strncpy() by strscpy()")
> > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
>
> This patch results in the following sparse warnings:
>
> sparse: WARNINGS
> SPARSE:mtk-vpu/mtk_vpu.c mtk-vpu/mtk_vpu.c:834:52:  warning: incorrect type in argument 3 (incompatible argument 1 (different address spaces))
> SPARSE:mtk-vpu/mtk_vpu.c mtk-vpu/mtk_vpu.c:609:29:  warning: dereference of noderef expression
> SPARSE:mtk-vpu/mtk_vpu.c mtk-vpu/mtk_vpu.c:613:35:  warning: dereference of noderef expression
> SPARSE:mtk-vpu/mtk_vpu.c mtk-vpu/mtk_vpu.c:614:35:  warning: dereference of noderef expression
>
> Can you take a look?
>
> Regards,
>
>         Hans
>
Thanks, I'll send a v2 to fix this

Patch
diff mbox series

diff --git a/drivers/media/platform/mtk-vpu/mtk_vpu.c b/drivers/media/platform/mtk-vpu/mtk_vpu.c
index a768707abb94..e705e85d6f5a 100644
--- a/drivers/media/platform/mtk-vpu/mtk_vpu.c
+++ b/drivers/media/platform/mtk-vpu/mtk_vpu.c
@@ -600,13 +600,16 @@  int vpu_load_firmware(struct platform_device *pdev)
 }
 EXPORT_SYMBOL_GPL(vpu_load_firmware);
 
-static void vpu_init_ipi_handler(void *data, unsigned int len, void *priv)
+static void vpu_init_ipi_handler(void __iomem *data, unsigned int len,
+				 void *priv)
 {
 	struct mtk_vpu *vpu = (struct mtk_vpu *)priv;
-	struct vpu_run *run = (struct vpu_run *)data;
+	struct vpu_run __iomem *run = data;
 
 	vpu->run.signaled = run->signaled;
-	strscpy(vpu->run.fw_ver, run->fw_ver, sizeof(vpu->run.fw_ver));
+	memcpy_fromio(vpu->run.fw_ver, run->fw_ver, sizeof(vpu->run.fw_ver));
+	/* Make sure the string is NUL-terminated */
+	vpu->run.fw_ver[sizeof(vpu->run.fw_ver) - 1] = '\0';
 	vpu->run.dec_capability = run->dec_capability;
 	vpu->run.enc_capability = run->enc_capability;
 	wake_up_interruptible(&vpu->run.wq);