Re: [PATCH] media: qcom: camss: vfe: Fix out-of-bounds access in vfe_isr_reg_update()

[Bryan O'Donoghue <bryan.odonoghue@linaro.org>]

On 27/12/2025 10:24, Alper Ak wrote:
> vfe_isr() iterates using MSM_VFE_IMAGE_MASTERS_NUM(7) as the loop
> bound and passes the index to vfe_isr_reg_update(). However,
> vfe->line[] array is defined with VFE_LINE_NUM_MAX(4):
> 
>      struct vfe_line line[VFE_LINE_NUM_MAX];
> 
> When index is 4, 5, 6, the access to vfe->line[line_id] exceeds
> the array bounds and resulting in out-of-bounds memory access.
> 
> Add a bounds check to ensure line_id is within valid range before
> accessing the array.
> 
> Fixes: 4edc8eae715c ("media: camss: Add initial support for VFE hardware version Titan 480")
> Signed-off-by: Alper Ak <alperyasinak1@gmail.com>
> ---
>   drivers/media/platform/qcom/camss/camss-vfe-480.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/media/platform/qcom/camss/camss-vfe-480.c b/drivers/media/platform/qcom/camss/camss-vfe-480.c
> index 4feea590a47b..fac111135c78 100644
> --- a/drivers/media/platform/qcom/camss/camss-vfe-480.c
> +++ b/drivers/media/platform/qcom/camss/camss-vfe-480.c
> @@ -237,6 +237,9 @@ static void vfe_isr_reg_update(struct vfe_device *vfe, enum vfe_line_id line_id)
>   	struct vfe_output *output;
>   	unsigned long flags;
>   
> +	if (line_id >= VFE_LINE_NUM_MAX)
> +		return;
> +
>   	spin_lock_irqsave(&vfe->output_lock, flags);
>   	vfe_reg_update_clear(vfe, line_id);
>   

A logical bug.

I think we shouldn't be calling this function at all with a index that 
is too large though.

Something like this instead. An explicit loop for the output lines and 
another loop for the write-master completions.

diff --git a/drivers/media/platform/qcom/camss/camss-vfe-480.c 
b/drivers/media/platform/qcom/camss/camss-vfe-480.c
index 4feea590a47bc..d73f733fde045 100644
--- a/drivers/media/platform/qcom/camss/camss-vfe-480.c
+++ b/drivers/media/platform/qcom/camss/camss-vfe-480.c
@@ -202,11 +202,13 @@ static irqreturn_t vfe_isr(int irq, void *dev)
                 writel_relaxed(status, vfe->base + VFE_BUS_IRQ_CLEAR(0));
                 writel_relaxed(1, vfe->base + VFE_BUS_IRQ_CLEAR_GLOBAL);

-               /* Loop through all WMs IRQs */
-               for (i = 0; i < MSM_VFE_IMAGE_MASTERS_NUM; i++) {
+               for (i = 0; i < MAX_VFE_OUTPUT_LINES; i++) {
                         if (status & BUS_IRQ_MASK_0_RDI_RUP(vfe, i))
                                 vfe_isr_reg_update(vfe, i);
+               }

+               /* Loop through all WMs IRQs */
+               for (i = 0; i < MSM_VFE_IMAGE_MASTERS_NUM; i++) {
                         if (status & BUS_IRQ_MASK_0_COMP_DONE(vfe, 
RDI_COMP_GROUP(i)))
                                 vfe_buf_done(vfe, i);
                 }

---
bod