On Fri, 2018-02-16 at 10:43 +0100, Norbert Manthey wrote:
> The current implementation will leak a byte to the log via memmove. The
> specified 27 bytes are off-by-one, as the payload is 25 bytes, and the
> termination character is only one byte large. To avoid this, factor out
> the error message, and furthermore make the second parameter of the
> append_entry function const.
>
> Fixes: 4562236b3bc0 ("drm/amd/dc: Add dc display driver (v2)")
>
> The full trace is as follows:
>
> In function ‘memmove’,
> from ‘append_entry’ at
> drivers/gpu/drm/amd/display/dc/basics/logger.c:257:2,
> from ‘dm_logger_append_va’ at
> drivers/gpu/drm/amd/display/dc/basics/logger.c:348:4
> detected read beyond size of object passed as 2nd parameter
>
> Signed-off-by: Norbert Manthey <nmant...@amazon.de>
That same code exists in a different form in at least 4.15 so
Cc: sta...@vger.kernel.org
> Cc: Alex Deucher <alexander.deuc...@amd.com>
> Cc: "Christian König" <christian.koe...@amd.com>
> Cc: "David (ChunMing) Zhou" <david1.z...@amd.com>
> Cc: David Airlie <airl...@linux.ie>
> Cc: Harry Wentland <harry.wentl...@amd.com>
> Cc: Tony Cheng <tony.ch...@amd.com>
> Cc: Yongqiang Sun <yongqiang....@amd.com>
> Cc: Aric Cyr <aric....@amd.com>
> Cc: Colin Ian King <colin.k...@canonical.com>
> Cc: Corbin McElhanney <corbin.mcelhan...@amd.com>
> Cc: Jordan Lazare <jordan.laz...@amd.com>
> Cc: Dmytro Laktyushkin <dmytro.laktyush...@amd.com>
> Cc: amd-...@lists.freedesktop.org
> Cc: dri-de...@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
>
> ---
> drivers/gpu/drm/amd/display/dc/basics/logger.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/basics/logger.c
> b/drivers/gpu/drm/amd/display/dc/basics/logger.c
> index 180a9d6..958070c 100644
> --- a/drivers/gpu/drm/amd/display/dc/basics/logger.c
> +++ b/drivers/gpu/drm/amd/display/dc/basics/logger.c
> @@ -243,7 +243,7 @@ static void log_heading(struct log_entry *entry)
>
> static void append_entry(
> struct log_entry *entry,
> - char *buffer,
> + const char *buffer,
> uint32_t buf_size)
> {
> if (!entry->buf ||
> @@ -345,7 +345,9 @@ void dm_logger_append_va(
> if (size < LOG_MAX_LINE_SIZE - 1) {
> append_entry(entry, buffer, size);
> } else {
> - append_entry(entry, "LOG_ERROR, line too long\n", 27);
> + static const char msg[] = "LOG_ERROR, line too long\n";
> +
> + append_entry(entry, msg, sizeof(msg));
> }
> }
> }
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