Message ID | 87poktjmfn.fsf@esperi.org.uk |
---|---|
State | New |
Headers | show |
On 12/15/2016 03:29 PM, Nix wrote: > On 15 Dec 2016, Florian Weimer told this: > >> On 12/15/2016 03:15 PM, Nix wrote: >> >>> Possible fix, untested: >>> >>> diff --git a/sysdeps/generic/symbol-hacks.h b/sysdeps/generic/symbol-hacks.h >>> index 36908b5..0679354 100644 >>> --- a/sysdeps/generic/symbol-hacks.h >>> +++ b/sysdeps/generic/symbol-hacks.h >>> @@ -7,5 +7,7 @@ asm ("memcpy = __GI_memcpy"); >>> >>> /* -fstack-protector generates calls to __stack_chk_fail, which need >>> similar adjustments to avoid going through the PLT. */ >>> +#if defined __SSP__ || defined __SSP_ALL__ || defined __SSP_STRONG__ >>> asm ("__stack_chk_fail = __stack_chk_fail_local"); >>> #endif >>> +#endif >> >> The condition looks rather brittle. What if GCC grows an -fstack-protector-light switch and __SSP_LIGHT__ macro? > > We'd need to change configure.ac before that would have an effect in any > case... but it does seem likely that changing this too would be > overlooked. Right. >> I wonder if it's better to add something to $(no-stack-protector) and use that in the conditional. > > That was my other option, but the total absence of anything in > configure.ac passing -D made me think twice. > > Something like this? (even more untested than the last one, if > possible -- but adds a new possibility: we can now differentiate between > "glibc built without stack protector" and "glibc built with stack > protector but this file doesn't have it" without relying on GCC > predefined macros. The __WITH_ naming scheme is completely arbitrary > and I can change it to anything you prefer.) WITH_STACK_PROTECTOR (without the leading underscores) looks okay to me because it's only used at build time. Or you could call it STACK_PROTECTOR_LEVEL, to match the other variable. > diff --git a/configure.ac b/configure.ac > index 2396c1f..8bb8c2c 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -638,18 +638,18 @@ LIBC_TRY_CC_OPTION([$CFLAGS $CPPFLAGS -Werror -fstack-protector-all], > stack_protector= > no_stack_protector= > if test "$libc_cv_ssp" = yes; then > - no_stack_protector="-fno-stack-protector" > + no_stack_protector="-fno-stack-protector -D__WITH_STACK_PROTECTOR=0" > AC_DEFINE(HAVE_CC_NO_STACK_PROTECTOR) > fi > > if test "$enable_stack_protector" = yes && test "$libc_cv_ssp" = yes; then > - stack_protector="-fstack-protector" > + stack_protector="-fstack-protector -D__WITH_STACK_PROTECTOR=1" > AC_DEFINE(STACK_PROTECTOR_LEVEL, 1) > elif test "$enable_stack_protector" = all && test "$libc_cv_ssp_all" = yes; then > - stack_protector="-fstack-protector-all" > + stack_protector="-fstack-protector-all -D__WITH_STACK_PROTECTOR=2" > AC_DEFINE(STACK_PROTECTOR_LEVEL, 2) > elif test "$enable_stack_protector" = strong && test "$libc_cv_ssp_strong" = yes; then > - stack_protector="-fstack-protector-strong" > + stack_protector="-fstack-protector-strong -D__WITH_STACK_PROTECTOR=3" > AC_DEFINE(STACK_PROTECTOR_LEVEL, 3) > fi > AC_SUBST(libc_cv_ssp) > diff --git a/sysdeps/generic/symbol-hacks.h b/sysdeps/generic/symbol-hacks.h > index 36908b5..12b4fe7 100644 > --- a/sysdeps/generic/symbol-hacks.h > +++ b/sysdeps/generic/symbol-hacks.h > @@ -7,5 +7,7 @@ asm ("memcpy = __GI_memcpy"); > > /* -fstack-protector generates calls to __stack_chk_fail, which need > similar adjustments to avoid going through the PLT. */ > +#if defined __WITH_STACK_PROTECTOR && __WITH_STACK_PROTECTOR > 0 > asm ("__stack_chk_fail = __stack_chk_fail_local"); > #endif > +#endif The new #if/#endif need to be indented. Thanks, Florian
diff --git a/configure.ac b/configure.ac index 2396c1f..8bb8c2c 100644 --- a/configure.ac +++ b/configure.ac @@ -638,18 +638,18 @@ LIBC_TRY_CC_OPTION([$CFLAGS $CPPFLAGS -Werror -fstack-protector-all], stack_protector= no_stack_protector= if test "$libc_cv_ssp" = yes; then - no_stack_protector="-fno-stack-protector" + no_stack_protector="-fno-stack-protector -D__WITH_STACK_PROTECTOR=0" AC_DEFINE(HAVE_CC_NO_STACK_PROTECTOR) fi if test "$enable_stack_protector" = yes && test "$libc_cv_ssp" = yes; then - stack_protector="-fstack-protector" + stack_protector="-fstack-protector -D__WITH_STACK_PROTECTOR=1" AC_DEFINE(STACK_PROTECTOR_LEVEL, 1) elif test "$enable_stack_protector" = all && test "$libc_cv_ssp_all" = yes; then - stack_protector="-fstack-protector-all" + stack_protector="-fstack-protector-all -D__WITH_STACK_PROTECTOR=2" AC_DEFINE(STACK_PROTECTOR_LEVEL, 2) elif test "$enable_stack_protector" = strong && test "$libc_cv_ssp_strong" = yes; then - stack_protector="-fstack-protector-strong" + stack_protector="-fstack-protector-strong -D__WITH_STACK_PROTECTOR=3" AC_DEFINE(STACK_PROTECTOR_LEVEL, 3) fi AC_SUBST(libc_cv_ssp) diff --git a/sysdeps/generic/symbol-hacks.h b/sysdeps/generic/symbol-hacks.h index 36908b5..12b4fe7 100644 --- a/sysdeps/generic/symbol-hacks.h +++ b/sysdeps/generic/symbol-hacks.h @@ -7,5 +7,7 @@ asm ("memcpy = __GI_memcpy"); /* -fstack-protector generates calls to __stack_chk_fail, which need similar adjustments to avoid going through the PLT. */ +#if defined __WITH_STACK_PROTECTOR && __WITH_STACK_PROTECTOR > 0 asm ("__stack_chk_fail = __stack_chk_fail_local"); #endif +#endif