From 7b93e98143c376ed09bfd30658b8641d4a36e77e Mon Sep 17 00:00:00 2001 From: Rodrigo Rebello Date: Thu, 12 Nov 2015 12:04:28 -0200 Subject: [PATCH] configure: use appropriate code fragment for -fstack-protector checks Cc: qemu-trivial@nongnu.org The check for stack-protector support consisted in compiling and linking the test program below (output by function write_c_skeleton()) with the compiler flag -fstack-protector-strong first and then with -fstack-protector-all if the first one failed to work: int main(void) { return 0; } This caused false positives when using certain toolchains in which the compiler accepts -fstack-protector-strong but no support is provided by the C library, since in this stack-protector variant the compiler emits canary code only for functions that meet specific conditions (local arrays, memory references to local variables, etc.) and the code fragment under test included none of them (hence no stack protection code generated, no link failure). This fix modifies the test program used for -fstack-protector checks to meet conditions which cause the compiler to generate canary code in all variants. Upstream status: sent https://patchwork.ozlabs.org/patch/543357/ Signed-off-by: Rodrigo Rebello --- configure | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/configure b/configure index cd219d8..27d7b3c 100755 --- a/configure +++ b/configure @@ -1471,6 +1471,16 @@ for flag in $gcc_flags; do done if test "$stack_protector" != "no"; then + cat > $TMPC << EOF +int main(int argc, char *argv[]) +{ + char arr[64], *p = arr, *c = argv[0]; + while (*c) { + *p++ = *c++; + } + return 0; +} +EOF gcc_flags="-fstack-protector-strong -fstack-protector-all" sp_on=0 for flag in $gcc_flags; do -- 2.1.4