[FFmpeg-devel] [PATCH 2/3] configure: Support for HEASLR on mingw targets

[Alex Smith]

From: Alex Smith <alex.smith at warpsharp.info>

The appropriate flag for HEASLR (--high-entropy-va) is scheduled for
inclusion in the next version of binutils (2.25), doesn't hurt to
include it a little early.

Also set the image base >4GB so higher entropy gets applied to image
base randomization when used with HEASLR (8 -> 17 bits of
randomization).  Windows does this for compatibility because of "latent
pointer truncation issues".

Signed-off-by: Alex Smith <alex.smith at warpsharp.info>
---
 configure | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/configure b/configure
index d6ab35a..0c60c03 100755
--- a/configure
+++ b/configure
@@ -4400,6 +4400,10 @@ case $target_os in
             add_ldexeflags -Wl,--pic-executable,-e,_mainCRTStartup
         elif enabled x86_64; then
             add_ldexeflags -Wl,--pic-executable,-e,mainCRTStartup
+            check_ldflags -Wl,--high-entropy-va # binutils 2.25
+            # Set image base >4GB for extra entropy with HEASLR
+            add_ldexeflags -Wl,--image-base,0x140000000
+            append SHFLAGS -Wl,--image-base,0x180000000
         fi
         ;;
     win32|win64)
-- 
1.9.5.msysgit.0