From: Paulo Zanoni Date: Tue, 17 Sep 2013 14:14:10 +0000 (-0300) Subject: drm/i915: WARN is the DP aux read or write is too big X-Git-Tag: firefly_0821_release~176^2~4694^2~201^2~23 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=46a5ae9f82719aa6e3c9c0d344772f475a335161;p=firefly-linux-kernel-4.4.55.git drm/i915: WARN is the DP aux read or write is too big So far we control everything and nothing exceeds the current limits, but (i) we never think about these limits when reviewing patches, (ii) not all the callers check the return values and (iii) if we ever hit any of these messages, we'll have to fix the code that added the bad message. The current limit for these messages is 20 since we only have 5 data registers on all the current gens. The checks inside intel_dp_aux_native_{write,read} are to prevent buffer overflows. The check inside intel_dp_aux_ch is to prevent writing past our 5 data registers. Signed-off-by: Paulo Zanoni Reviewed-by: Jani Nikula Signed-off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index e61ba90fb1b3..9770160c0085 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -436,6 +436,12 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, goto out; } + /* Only 5 data registers! */ + if (WARN_ON(send_bytes > 20 || recv_size > 20)) { + ret = -E2BIG; + goto out; + } + while ((aux_clock_divider = get_aux_clock_divider(intel_dp, clock++))) { /* Must try at least 3 times according to DP spec */ for (try = 0; try < 5; try++) { @@ -526,9 +532,10 @@ intel_dp_aux_native_write(struct intel_dp *intel_dp, int msg_bytes; uint8_t ack; + if (WARN_ON(send_bytes > 16)) + return -E2BIG; + intel_dp_check_edp(intel_dp); - if (send_bytes > 16) - return -1; msg[0] = AUX_NATIVE_WRITE << 4; msg[1] = address >> 8; msg[2] = address & 0xff; @@ -569,6 +576,9 @@ intel_dp_aux_native_read(struct intel_dp *intel_dp, uint8_t ack; int ret; + if (WARN_ON(recv_bytes > 19)) + return -E2BIG; + intel_dp_check_edp(intel_dp); msg[0] = AUX_NATIVE_READ << 4; msg[1] = address >> 8;