[MSAN] extend prctl interceptor to support PR_SCHED_CORE

[kda]

narrow intercept by checking second parameter.

[vitalybuka]

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

1368

Can you add a trivial test in test/sanitizer_common?

[kda]

added unit test

[kda]

trim includes from unit test

[eugenis]

LGTM

compiler-rt/test/sanitizer_common/TestCases/Linux/prctl.cpp

23

I don't understand the api well enough to know if cookie value of 0 is invalid, or just merely very unlikely.

[kda]

compiler-rt/test/sanitizer_common/TestCases/Linux/prctl.cpp

23

Found it: https://elixir.bootlin.com/linux/v5.14/source/kernel/sched/core_sched.c#L170

If zero, then generates error.

[lkail]

Hi, this patch is breaking https://lab.llvm.org/buildbot/#/builders/37/builds/12263 https://lab.llvm.org/buildbot/#/builders/19/builds/10280, could you please take a look?

[abrachet]

Some more breakages here https://ci.chromium.org/ui/p/fuchsia/builders/toolchain.ci/clang-linux-arm64/b8817448868122486465/overview

[kda]

committed: https://reviews.llvm.org/rG5562d9b3c006f3e376d98ee7b9f3c6c8608ddbee
Should fix builds.

[kda]

gasp. I missed one symbol.
Should be fixed now. I hope.

https://reviews.llvm.org/rGb401d2a43cf6ba9b2c8b87a58e8d78099bce828f

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

 #endif
 
 #if SANITIZER_INTERCEPT_PRCTL
 INTERCEPTOR(int, prctl, int option, unsigned long arg2, unsigned long arg3,
             unsigned long arg4, unsigned long arg5) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, prctl, option, arg2, arg3, arg4, arg5);
   static const int PR_SET_NAME = 15;
+  static const int PR_SCHED_CORE = 62;
+  static const int PR_SCHED_CORE_GET = 0;
   int res = REAL(prctl(option, arg2, arg3, arg4, arg5));
   if (option == PR_SET_NAME) {
     char buff[16];
     internal_strncpy(buff, (char *)arg2, 15);
     buff[15] = 0;
     COMMON_INTERCEPTOR_SET_THREAD_NAME(ctx, buff);
+  } else if (res != -1 && option == PR_SCHED_CORE && arg2 == PR_SCHED_CORE_GET) {
+    COMMON_INTERCEPTOR_WRITE_RANGE(ctx, (u64*)(arg5), sizeof(u64));
   }
   return res;
 }
 #define INIT_PRCTL COMMON_INTERCEPT_FUNCTION(prctl)
 #else
 #define INIT_PRCTL
 #endif  // SANITIZER_INTERCEPT_PRCTL
 

compiler-rt/test/sanitizer_common/TestCases/Linux/prctl.cpp

+// RUN: %clangxx %s -o %t && %run %t %p
+
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <sys/prctl.h>
+
+int main() {
+
+  int res;
+  res = prctl(PR_SCHED_CORE, PR_SCHED_CORE_CREATE, 0, 0, 0);
+  if (res < 0) {
+    assert(errno == EINVAL);
+    return 0;
+  }
+
+  uint64_t cookie = 0;
+  res = prctl(PR_SCHED_CORE, PR_SCHED_CORE_GET, 0, 0, &cookie);
+  if (res < 0) {
+    assert(errno == EINVAL);
+  } else {
+    assert(cookie != 0);
+  }
+
+  return 0;
+}