Re: [PATCH v2 4/4] venus: hfi_parser: Add check to keep the number of codecs within range
From: Bryan O'Donoghue
Date: Fri Aug 11 2023 - 14:51:43 EST
On 11/08/2023 17:02, Vikash Garodia wrote:
On 8/11/2023 4:11 PM, Bryan O'Donoghue wrote:
On 11/08/2023 09:49, Vikash Garodia wrote:
On 8/11/2023 2:12 PM, Bryan O'Donoghue wrote:
On 11/08/2023 07:04, Vikash Garodia wrote:
On 8/10/2023 5:03 PM, Bryan O'Donoghue wrote:
On 10/08/2023 03:25, Vikash Garodia wrote:
+ if (hweight_long(core->dec_codecs) + hweight_long(core->enc_codecs) >
MAX_CODEC_NUM)
+ return;
+
Shouldn't this be >= ?
Not needed. Lets take a hypothetical case when core->dec_codecs has initial 16
(0-15) bits set and core->enc_codecs has next 16 bits (16-31) set. The bit
count
would be 32. The codec loop after this check would run on caps array index
0-31.
I do not see a possibility for OOB access in this case.
struct hfi_plat_caps caps[MAX_CODEC_NUM];
---
bod
Are you not doing a general defensive coding pass in this series ie
"[PATCH v2 2/4] venus: hfi: fix the check to handle session buffer requirement"
In "PATCH v2 2/4", there is a possibility if the check does not consider "=".
Here in this patch, I do not see a possibility.
---
bod
But surely hweight_long(core->dec_codecs) + hweight_long(core->enc_codecs) ==
MAX_CODEC_NUM is an invalid offset ?
No, it isn't. Please run through the loop with the bitmasks added upto 32 and
see if there is a possibility of OOB.
IDK Vikash, the logic here seems suspect.
We have two loops that check for up to 32 indexes per loop. Why not have
a capabilities index that can accommodate all 64 bits ?
Why is it valid to have 16 encoder bits and 16 decoder bits but invalid
to have 16 encoder bits with 17 decoder bits ? While at the same time
valid to have 0 encoder bits but 17 decoder bits ?
---
bod