From 23163df24cf96107ee8ccb372db20f49e9d88948 Mon Sep 17 00:00:00 2001 From: Carl Worth Date: Mon, 18 Aug 2014 11:36:12 -0700 Subject: [PATCH] glcpp: Don't use alternation in the lookahead for empty pragmas. We've found that there's a buffer overrun bug in flex that's triggered by using alternation in a lookahead pattern. Fortunately, we don't need to match the exact {NEWLINE} expression to detect an empty pragma. It suffices to verify that there are no non-space characters before any newline character. So we can use a simple [\r\n] to get the desired behavior while avoiding the flex bug. Fixes the regression of piglit's 17000-consecutive-chars-identifier test, (which has been crashing since commit 04e40fd337a244ee77ef9553985e9398ff0344af ). Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82472 Signed-off-by: Carl Worth Reviewed-by: Kenneth Graunke CC: --- src/glsl/glcpp/glcpp-lex.l | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/src/glsl/glcpp/glcpp-lex.l b/src/glsl/glcpp/glcpp-lex.l index 98d500ec0be..fa9aa506912 100644 --- a/src/glsl/glcpp/glcpp-lex.l +++ b/src/glsl/glcpp/glcpp-lex.l @@ -289,8 +289,14 @@ HEXADECIMAL_INTEGER 0[xX][0-9a-fA-F]+[uU]? } /* Swallow empty #pragma directives, (to avoid confusing the - * downstream compiler). */ -pragma{HSPACE}*/{NEWLINE} { + * downstream compiler). + * + * Note: We use a simple regular expression for the lookahead + * here. Specifically, we cannot use the complete {NEWLINE} expression + * since it uses alternation and we've found that there's a flex bug + * where using alternation in the lookahead portion of a pattern + * triggers a buffer overrun. */ +pragma{HSPACE}*/[\r\n] { BEGIN INITIAL; } -- 2.30.2