From d81a67cc1bfdc3efed8590ee4e07a40b198908ba Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Fri, 29 Jan 2016 14:52:26 +0200 Subject: [PATCH] drm/i915: Sanity check DP AUX message buffer and size While we are calling intel_dp_aux_transfer() with msg->size=0 whenever msg->buffer is NULL, passing NULL to memcpy() is undefined according to the ISO C standard. I haven't found any notes about this in the GNU C's or the kernel's documentation of the function and can't imagine what it would do with the NULL ptr. To better document this use of the parameters it still make sense to add an explicit check for this to the code. Signed-off-by: Imre Deak Reviewed-by: David Weinehall Link: http://patchwork.freedesktop.org/patch/msgid/1454071949-24677-1-git-send-email-imre.deak@intel.com --- drivers/gpu/drm/i915/intel_dp.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index f44aba1019b8..a073f04a5330 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -979,7 +979,10 @@ intel_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) if (WARN_ON(txsize > 20)) return -E2BIG; - memcpy(txbuf + HEADER_SIZE, msg->buffer, msg->size); + if (msg->buffer) + memcpy(txbuf + HEADER_SIZE, msg->buffer, msg->size); + else + WARN_ON(msg->size); ret = intel_dp_aux_ch(intel_dp, txbuf, txsize, rxbuf, rxsize); if (ret > 0) { -- 2.20.1