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Subject[PATCH] media: venus: fix possible buffer overlow casued bad DMA value in venus_sfr_print()
Date
The value hdev->sfr.kva is stored in DMA memory, and it is assigned to
sfr, so sfr->buf_size can be modified at anytime by malicious hardware.
In this case, a buffer overflow may happen when the code
"sfr->data[sfr->buf_size - 1]" is executed.

To fix this possible bug, sfr->buf_size is assigned to a local variable,
and then this variable is checked before being used.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
drivers/media/platform/qcom/venus/hfi_venus.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/qcom/venus/hfi_venus.c b/drivers/media/platform/qcom/venus/hfi_venus.c
index 0d8855014ab3..4251a9e47a1b 100644
--- a/drivers/media/platform/qcom/venus/hfi_venus.c
+++ b/drivers/media/platform/qcom/venus/hfi_venus.c
@@ -960,18 +960,23 @@ static void venus_sfr_print(struct venus_hfi_device *hdev)
{
struct device *dev = hdev->core->dev;
struct hfi_sfr *sfr = hdev->sfr.kva;
+ u32 buf_size;
void *p;

if (!sfr)
return;

- p = memchr(sfr->data, '\0', sfr->buf_size);
+ buf_size = sfr->buf_size;
+ if (buf_size > 1)
+ return;
+
+ p = memchr(sfr->data, '\0', buf_size);
/*
* SFR isn't guaranteed to be NULL terminated since SYS_ERROR indicates
* that Venus is in the process of crashing.
*/
if (!p)
- sfr->data[sfr->buf_size - 1] = '\0';
+ sfr->data[buf_size - 1] = '\0';

dev_err_ratelimited(dev, "SFR message from FW: %s\n", sfr->data);
}
--
2.17.1
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