On Fri, May 27, 2022 at 11:50:41AM +0100, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>
> Ensure buffer is null terminated at the point where the read ended and not
> at the end of the whole buffer. Otherwise string parsing can stray into
> un-initialised memory.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Reviewed-by: Petri Latvala <petri.latvala@xxxxxxxxx>
> ---
> lib/igt_drm_fdinfo.c | 8 ++++----
> lib/igt_drm_fdinfo.h | 4 ++--
> 2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/lib/igt_drm_fdinfo.c b/lib/igt_drm_fdinfo.c
> index b422f67a4ace..250d9e8917f2 100644
> --- a/lib/igt_drm_fdinfo.c
> +++ b/lib/igt_drm_fdinfo.c
> @@ -44,12 +44,12 @@ static size_t read_fdinfo(char *buf, const size_t sz, int at, const char *name)
> if (fd < 0)
> return 0;
>
> - buf[sz - 1] = 0;
> - count = read(fd, buf, sz);
> - buf[sz - 1] = 0;
> + count = read(fd, buf, sz - 1);
> + if (count > 0)
> + buf[count - 1] = 0;
> close(fd);
>
> - return count;
> + return count > 0 ? count : 0;
> }
>
> static int parse_engine(char *line, struct drm_client_fdinfo *info,
> diff --git a/lib/igt_drm_fdinfo.h b/lib/igt_drm_fdinfo.h
> index 5db63e28b07e..8759471615bd 100644
> --- a/lib/igt_drm_fdinfo.h
> +++ b/lib/igt_drm_fdinfo.h
> @@ -46,7 +46,7 @@ struct drm_client_fdinfo {
> * igt_parse_drm_fdinfo: Parses the drm fdinfo file
> *
> * @drm_fd: DRM file descriptor
> - * @info: Structure to populate with read data
> + * @info: Structure to populate with read data. Must be zeroed.
> *
> * Returns the number of valid drm fdinfo keys found or zero if not all
> * mandatory keys were present or no engines found.
> @@ -58,7 +58,7 @@ unsigned int igt_parse_drm_fdinfo(int drm_fd, struct drm_client_fdinfo *info);
> *
> * @dir: File descriptor pointing to /proc/pid/fdinfo directory
> * @fd: String representation of the file descriptor number to parse.
> - * @info: Structure to populate with read data
> + * @info: Structure to populate with read data. Must be zeroed.
> *
> * Returns the number of valid drm fdinfo keys found or zero if not all
> * mandatory keys were present or no engines found.
> --
> 2.32.0
>
