New: Flag '-Wa, --noexecstack' is missing when building uclibc with newer binutils
https://bugs.busybox.net/show_bug.cgi?id=12801
Bug ID: 12801
Summary: Flag '-Wa,--noexecstack' is missing when building
uclibc with newer binutils
Product: buildroot
Version: unspecified
Hardware: PC
OS: Linux
Status: NEW
Severity: major
Priority: P5
Component: Other
Assignee: unassigned at buildroot.uclibc.org
Reporter: m.patzlaff at pilz.de
CC: buildroot at uclibc.org
Target Milestone: ---
Created attachment 8436
--> https://bugs.busybox.net/attachment.cgi?id=8436&action=edit
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.
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[Buildroot] [Bug 12801] Flag '-Wa, --noexecstack' is missing when building uclibc with newer binutils
https://bugs.busybox.net/show_bug.cgi?id=12801
--- Comment #1 from Marcel Patzlaff <[email protected]> --- Created attachment 8441
--> https://bugs.busybox.net/attachment.cgi?id=8441&action=edit
Partial log of the OK case
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[Buildroot] [Bug 12801] Flag '-Wa, --noexecstack' is missing when building uclibc with newer binutils
In reply to bugzilla at busybox.nethttps://bugs.busybox.net/show_bug.cgi?id=12801
--- Comment #2 from Marcel Patzlaff <[email protected]> --- Created attachment 8446
--> https://bugs.busybox.net/attachment.cgi?id=8446&action=edit
Partial log of the failure case
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[Buildroot] [Bug 12801] Flag '-Wa, --noexecstack' is missing when building uclibc with newer binutils
In reply to bugzilla at busybox.nethttps://bugs.busybox.net/show_bug.cgi?id=12801
Marcel Patzlaff <[email protected]> changed:
What |Removed |Added
----------------------------------------------------------------------------
OS|Linux |All
Target| |ARM Cortex A9
Build| |x86_64 laptop
Hardware|PC |AllSignature · 2 lines
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[Buildroot] [Bug 12801] Flag '-Wa, --noexecstack' is missing when building uclibc with newer binutils
In reply to bugzilla at busybox.nethttps://bugs.busybox.net/show_bug.cgi?id=12801
Marcel Patzlaff <[email protected]> changed:
What |Removed |Added
----------------------------------------------------------------------------
Product|buildroot |uClibc
Component|Other |Other
Assignee|unassigned at buildroot.uclibc |unassigned at uclibc.org
|.org |
CC| |uclibc-cvs at uclibc.org--- Comment #3 from Marcel Patzlaff <[email protected]> ---
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.
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[Buildroot] [Bug 12801] Flag '-Wa, --noexecstack' is missing when building uclibc with newer binutils
In reply to bugzilla at busybox.nethttps://bugs.busybox.net/show_bug.cgi?id=12801
romain.naour at gmail.com changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at uclibc.org |wbx at openadk.org
--- Comment #4 from romain.naour at gmail.com ---
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:
See similar report and kernel commit:
https://lkml.org/lkml/2018/8/9/233
I'm adding Waldemar in Cc of this bug.
Best regards,
Romain
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[Buildroot] [Bug 12801] Flag '-Wa, --noexecstack' is missing when building uclibc with newer binutils
In reply to bugzilla at busybox.nethttps://bugs.busybox.net/show_bug.cgi?id=12801
--- Comment #5 from Marcel Patzlaff <[email protected]> --- Created attachment 8451
--> https://bugs.busybox.net/attachment.cgi?id=8451&action=edit
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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