On Tue, Oct 17, 2017 at 5:26 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > On Tue, Oct 17, 2017 at 8:23 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: >> On Tue, Oct 17, 2017 at 1:00 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: >>> Hi Kees, >>> >>> On my test box, current linux-next kernels fail to build due to the >>> patch that introduces CONFIG_CC_STACKPROTECTOR_AUTO, with my mainline >>> gcc >>> builds up to gcc-5.5.0. gcc-6 and higher work fine, as >>> scripts/gcc-x86_64-has-stack-protector.sh returns 'y' for those. >>> >>> Using the compilers provided by Ubuntu (4.6/4.7/4.8/4.9), everything >>> also works as expected, so my interpretation is that mainline gcc did >>> not enable the stack protector until gcc-6, while distributions did. >>> >>> Do you agree with that interpretation? >> >> It's probably a little different. I tried bisecting the gcc commit that fixed >> the issue for me, and ended up with this commit >> >> https://gitlab.indel.ch/thirdparty/gcc/commit/c14bac81551d6769741c2b1cc55e04d94fe8d3a7 >> >> that caused the target to change from x86_64-unknown-linux to >> x86_64-pc-linux, and apparently caused the compiler bootstrap >> to incorrectly identify the capabilities of the assembler. As a result, >> the assembler output inside of scripts/gcc-x86_64-has-stack-protector.sh >> that should be >> [snip] > > Yeah, %gs: vs __stack_chk_guard global. > > Do you know which gccs (of the past) had this? The commit I linked to went into gcc-6.1.0, everything before that version is affected for me. I tried gcc-4.{3,4,5,6,7,8,9} and gcc-5.5. I'm still trying to figure out which part of the config.guess change caused exactly fixed it and why. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
