[compiler-rt] r298305 - Bypass potential libc's sysconf wrappers for sysconf(_SC_PAGESIZE) call

[Vitaly Buka via llvm-commits]

Alex, could you please take a look?
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/1128/steps/check-sanitizer%20in%20gcc%20build/logs/stdio

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/mnt/b/sanitizer-buildbot1/sanitizer-x86_64-linux/build/llvm/projects/compiler-rt/lib/sanitizer_common/sanitizer_linux.cc:81:22:
fatal error: sys/auxv.h: No such file or directory
 #include <sys/auxv.h>
                      ^
compilation terminated.
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Error 1
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/mnt/b/sanitizer-buildbot1/sanitizer-x86_64-linux/build/llvm/projects/compiler-rt/lib/sanitizer_common/sanitizer_linux.cc:81:22:
fatal error: sys/auxv.h: No such file or directory
 #include <sys/auxv.h>
                      ^
compilation terminated.
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On Mon, Mar 20, 2017 at 2:15 PM Alex Shlyapnikov via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: alekseyshl
> Date: Mon Mar 20 16:03:28 2017
> New Revision: 298305
>
> URL: http://llvm.org/viewvc/llvm-project?rev=298305&view=rev
> Log:
> Bypass potential libc's sysconf wrappers for sysconf(_SC_PAGESIZE) call
>
> Summary:
> sysconf(_SC_PAGESIZE) is called very early, during sanitizer init and
> any instrumented code (a wrapper/interceptor will likely be instrumented)
> calling back to sanitizer before init is done will most surely crash.
>
> Reviewers: eugenis
>
> Subscribers: llvm-commits, kubamracek
>
> Differential Revision: https://reviews.llvm.org/D31092
>
> Added:
>
> compiler-rt/trunk/test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc
> Modified:
>     compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc
>
> Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc?rev=298305&r1=298304&r2=298305&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc (original)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc Mon Mar 20
> 16:03:28 2017
> @@ -78,6 +78,7 @@ extern char **environ;  // provided by c
>  #endif
>
>  #if SANITIZER_LINUX
> +#include <sys/auxv.h>
>  // <linux/time.h>
>  struct kernel_timeval {
>    long tv_sec;
> @@ -805,6 +806,8 @@ uptr GetPageSize() {
>    return 4096;
>  #elif SANITIZER_LINUX && (defined(__x86_64__) || defined(__i386__))
>    return EXEC_PAGESIZE;
> +#elif SANITIZER_LINUX
> +  return getauxval(AT_PAGESZ);
>  #else
>    return sysconf(_SC_PAGESIZE);  // EXEC_PAGESIZE may not be trustworthy.
>  #endif
>
> Added:
> compiler-rt/trunk/test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc?rev=298305&view=auto
>
> ==============================================================================
> ---
> compiler-rt/trunk/test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc
> (added)
> +++
> compiler-rt/trunk/test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc
> Mon Mar 20 16:03:28 2017
> @@ -0,0 +1,21 @@
> +// RUN: %clangxx -O2 %s -o %t && %run %t 2>&1 | FileCheck %s
> +
> +#include <stdio.h>
> +
> +extern "C" long sysconf(int name) {
> +  fprintf(stderr, "sysconf wrapper called\n");
> +  return 0;
> +}
> +
> +int main() {
> +  // All we need to check is that the sysconf() interceptor defined above
> was
> +  // not called. Should it get called, it will crash right there, any
> +  // instrumented code executed before sanitizer init is finished will
> crash
> +  // accessing non-initialized sanitizer internals. Even if it will not
> crash
> +  // in some configuration, it should never be called anyway.
> +  fprintf(stderr, "Passed\n");
> +  // CHECK-NOT: sysconf wrapper called
> +  // CHECK: Passed
> +  // CHECK-NOT: sysconf wrapper called
> +  return 0;
> +}
>
>
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