[PATCH v5 4/4] media: venus: hfi: add a check to handle OOB in sfr region

[Vikash Garodia]

sfr->buf_size is in shared memory and can be modified by malicious user.
OOB write is possible when the size is made higher than actual sfr data
buffer. Cap the size to allocated size for such cases.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: d96d3f30c0f2 ("[media] media: venus: hfi: add Venus HFI files")
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
Signed-off-by: Vikash Garodia <quic_vgarodia@xxxxxxxxxxx>
---
 drivers/media/platform/qcom/venus/hfi_venus.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/qcom/venus/hfi_venus.c b/drivers/media/platform/qcom/venus/hfi_venus.c
index 6b615270c5dae470c6fad408c9b5bc037883e56e..ab93757fff4b31910f05831170ca1a54f4925b2b 100644
--- a/drivers/media/platform/qcom/venus/hfi_venus.c
+++ b/drivers/media/platform/qcom/venus/hfi_venus.c
@@ -1041,18 +1041,26 @@ static void venus_sfr_print(struct venus_hfi_device *hdev)
 {
 	struct device *dev = hdev->core->dev;
 	struct hfi_sfr *sfr = hdev->sfr.kva;
+	u32 size;
 	void *p;
 
 	if (!sfr)
 		return;
 
-	p = memchr(sfr->data, '\0', sfr->buf_size);
+	size = sfr->buf_size;
+	if (!size)
+		return;
+
+	if (size > ALIGNED_SFR_SIZE)
+		size = ALIGNED_SFR_SIZE;
+
+	p = memchr(sfr->data, '\0', 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[size - 1] = '\0';
 
 	dev_err_ratelimited(dev, "SFR message from FW: %s\n", sfr->data);
 }

-- 
2.34.1