From 694fa0e332f8b3894a606619263c6ae38e4f6e20 Mon Sep 17 00:00:00 2001 From: Rodrigo Rebello Date: Mon, 16 Nov 2015 08:58:18 -0200 Subject: [PATCH] qemu: add patch to fix SSP support detection The QEMU configure script incorrectly assumes SSP is supported by the toolchain in some cases where the compiler accepts -fstack-protector* flags but the C library does not provide the necessary __stack_chk_*() functions. Even though a full compile and link test is performed by the script, this is done with a code fragment which does not actually meet any of the conditions required to cause the compiler to emit canary code when the -fstack-protector-strong variant is used. As no compile or link failure occurs in this case, a false positive is generated and a subsequent error is seen when the probe for pthreads is performed. The fix consists in patching the configure script to use a more appropriate test program for the SSP support checks. Fixes: http://autobuild.buildroot.net/results/efb/efbb4e940543894b8745bb405478a096c90a5ae2/ http://autobuild.buildroot.net/results/32d/32d6d984febad2dee1f0d31c5fa0aea823297096/ http://autobuild.buildroot.net/results/aa6/aa6e71c957fb6f07e7bded35a8e47be4dadd042c/ ...and many others. Signed-off-by: Rodrigo Rebello Acked-by: Arnout Vandecappelle (Essensium/Mind) Reviewed-by: Vicente Olivert Riera Tested-by: Vicente Olivert Riera Signed-off-by: Thomas Petazzoni --- ...propriate-code-fragment-for-fstack-p.patch | 58 +++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 package/qemu/0001-configure-use-appropriate-code-fragment-for-fstack-p.patch diff --git a/package/qemu/0001-configure-use-appropriate-code-fragment-for-fstack-p.patch b/package/qemu/0001-configure-use-appropriate-code-fragment-for-fstack-p.patch new file mode 100644 index 0000000000..9ebe334ffe --- /dev/null +++ b/package/qemu/0001-configure-use-appropriate-code-fragment-for-fstack-p.patch @@ -0,0 +1,58 @@ +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 + -- 2.30.2