| Summary: | Flag '-Wa,--noexecstack' is missing when building uclibc with newer binutils | ||
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| Product: | uClibc | Reporter: | Marcel Patzlaff <m.patzlaff> |
| Component: | Other | Assignee: | wbx |
| Status: | NEW --- | ||
| Severity: | major | CC: | buildroot, uclibc-cvs |
| Priority: | P5 | ||
| Version: | unspecified | ||
| Target Milestone: | --- | ||
| Hardware: | All | ||
| OS: | All | ||
| Host: | Target: | ARM Cortex A9 | |
| Build: | x86_64 laptop | ||
| Attachments: |
defconfig to reproduce the issue
Partial log of the OK case Partial log of the failure case Patch to fix the check_as Makefile macro. |
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Created attachment 8441 [details]
Partial log of the OK case
Created attachment 8446 [details]
Partial log of the failure case
I finally found what the problem is. The check_as macro in uclibc/Rules.mak does not function with newer binutils versions anymore. Executing the check manually yield: $ /opt/debug/buildroot_toolchain/usr/bin/arm-se-linux-uclibcgnueabihf-gcc -Wa,--noexecstack -Wa,-Z -c -o /dev/null -xassembler /dev/null || echo "WTF" Assembler messages: Fatal error: The input '/dev/null' and output '/dev/null' files are the same So basically, this seems to be uClibc bug. Hi Marcel, I'm able to reproduce the issue. Indeed the error message come from a new as check from binutils 2.31.x series: https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=67f846b59b32f3d704c601669409c2584383fea9 See similar report and kernel commit: https://lkml.org/lkml/2018/8/9/233 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9666d10a5677a494260d60d1fa0b73cc7646eb3 I'm adding Waldemar in Cc of this bug. Best regards, Romain Created attachment 8451 [details]
Patch to fix the check_as Makefile macro.
Please find a possible patch attached to fix this. I will also push it to the buildroot mailinglist, as the problem should be fixed really soon.
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Created attachment 8436 [details] defconfig to reproduce the issue When I upgraded buildroot from 2019.02.8 to 2020.02 and re-build my configuration I noticed that all binaries (executables and shared libraries) have the executable stack requested in the GNU_STACK program header. I did some research and also tried to narrow the cause. Eventually I found this: \ | binutils \ uclibc | 1.0.31 | 1.0.32 ------------------+-----------+--------------- 2.30 | fine | fine 2.31.1 | execstack | execstack 2.32 | execstack | execstack 2.33.1 | execstack | execstack So, until binutils 2.30 everything goes fine. Regardless of what GCC version (I tested with 4.9 and 8.3.0) I used, the uclibc libraries were marked with non-executable stack and thus all other binaries were OK too. But starting from binutils 2.31.1 something goes wrong. In the log for binutils 2.30 + uclibc 1.0.31 one can see, that the flag "-Wa,--noexecstack" is properly passed to the compiler. In the log for binutils 2.32 + uclibc 1.0.32 this flag is missing. And here is where I am lost. I can't figure out why because executing the flag detection in Rules.mak from uclibc manually returns the correct result. And I also double checked the security options in uclibc-menuconfig. To reproduce the results above it's best to use the attached defconfig on buildroot versions 2019.02.8 and 2020.02.