[Mesa-stable] [PATCH] st/mesa: use signed temporary variable to store _ColorDrawBufferIndexes

[Emil Velikov]

The temporary variable used to store _ColorDrawBufferIndexes must be
signed (GLint), otherwise the following conditional will be incorrectly
evaluated. Leading to crashes in the driver/mesa or accessing/writing
to arbitrary memory location. The bug dates back to 2009.

Cc: 10.0 9.2 9.1 <mesa-stable at lists.freedesktop.org>
Signed-off-by: Emil Velikov <emil.l.velikov at gmail.com>
---

Rather old bug, spotted after Marek's recent patches covering the
area. Curious if there is any particular reason why we do not
enable more compiler warning messages.

How do people feel on the subject of enabling more (all even) compiler
warnings on gcc compatible compilers ?

Just for laughs I'll set -Wall locally to see how many warning
messages gcc will produce. At least some of those would be usefull.

Cheers,
Emil
---
 src/mesa/state_tracker/st_cb_clear.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mesa/state_tracker/st_cb_clear.c b/src/mesa/state_tracker/st_cb_clear.c
index 87dccee..79124b3 100644
--- a/src/mesa/state_tracker/st_cb_clear.c
+++ b/src/mesa/state_tracker/st_cb_clear.c
@@ -444,7 +444,7 @@ st_Clear(struct gl_context *ctx, GLbitfield mask)
 
    if (mask & BUFFER_BITS_COLOR) {
       for (i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) {
-         GLuint b = ctx->DrawBuffer->_ColorDrawBufferIndexes[i];
+         GLint b = ctx->DrawBuffer->_ColorDrawBufferIndexes[i];
 
          if (b >= 0 && mask & (1 << b)) {
             struct gl_renderbuffer *rb
-- 
1.8.5.2