Andrii Nakryiko wrote:
> During recent refactorings, bpf_probe_read_kernel_str() started returning 0 on
> success, instead of amount of data successfully read. This majorly breaks
> applications relying on bpf_probe_read_kernel_str() and bpf_probe_read_str()
> and their results. Fix this by returning actual number of bytes read.
>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Fixes: 8d92db5c04d1 ("bpf: rework the compat kernel probe handling")
> Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
> ---
> kernel/trace/bpf_trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index e729c9e587a0..a3ac7de98baa 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -241,7 +241,7 @@ bpf_probe_read_kernel_str_common(void *dst, u32 size, const void *unsafe_ptr)
> if (unlikely(ret < 0))
> goto fail;
>
> - return 0;
> + return ret;
> fail:
> memset(dst, 0, size);
> return ret;
> --
> 2.24.1
>
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
