Re: [PATCH 2/4] perf: zstd: factor out zstd_init_{c,d}stream()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] perf: zstd_decompress_buffer() returns SIZE_MAX instead of 0 on error
--

commit 1d761c8689bb9c7209c96548d100b2308a92f2a5
Author: Ivan Shapovalov <intelfx@intelfx.name>

perf: zstd: factor out zstd_init_{c,d}stream()

Factor out functions to manage CStream/DStream in struct zstd_data
for reuse across multiple zstd (de)compression entry points.

> diff --git a/tools/perf/util/zstd.c b/tools/perf/util/zstd.c
> index af113660d1ce0..3af8910bb87cf 100644
> --- a/tools/perf/util/zstd.c
> +++ b/tools/perf/util/zstd.c
[ ... ]
> @@ -107,24 +139,14 @@ ssize_t zstd_compress_stream_to_records(struct zstd_data *data, void *dst, size_
>  size_t zstd_decompress_buffer(struct zstd_data *data, void *src, size_t src_size,
>  			      void *dst, size_t dst_size)
>  {
> -	size_t ret;
> +	ssize_t ret;
>  	ZSTD_inBuffer input = { src, src_size, 0 };
>  	ZSTD_outBuffer output = { dst, dst_size, 0 };
>  
> -	if (!data->dstream) {
> -		data->dstream = ZSTD_createDStream();
> -		if (data->dstream == NULL) {
> -			pr_err("Couldn't create decompression stream.\n");
> -			return 0;
> -		}
> +	ret = zstd_init_dstream(data);
> +	if (ret < 0)
> +		return ret;

[Severity: High]
Since zstd_decompress_buffer() returns a size_t, will returning a negative
error code here implicitly cast -1 to SIZE_MAX?

It looks like callers such as perf_session__process_compressed_event() check
for a 0 return to detect failure. If zstd_init_dstream() fails, wouldn't
returning SIZE_MAX cause the caller to treat it as a huge success,
potentially leading to massive out-of-bounds size increments?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261014-perf-zstd-v1-0-9652727886fa@intelfx.name?part=2