[scudo] Check for pvalloc overflow

Summary:
Previously we were rounding up the size passed to `pvalloc` to the next
multiple of page size no matter what. There is an overflow possibility that
wasn't accounted for. So now, return null in the event of an overflow. The man
page doesn't seem to indicate the errno to set in this particular situation,
but the glibc unit tests go for ENOMEM (https://code.woboq.org/userspace/glibc/malloc/tst-pvalloc.c.html#54)
so we'll do the same.
Update the aligned allocation funtions tests to check for properly aligned
returned pointers, and the `pvalloc` corner cases.

@alekseyshl: do you want me to do the same in the other Sanitizers?

Reviewers: alekseyshl

Reviewed By: alekseyshl

Subscribers: kubamracek, alekseyshl, llvm-commits

Differential Revision: https://reviews.llvm.org/D35818

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@309033 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_allocator_checks.h b/lib/sanitizer_common/sanitizer_allocator_checks.h
index 202916eae..b72f541a4 100644
--- a/lib/sanitizer_common/sanitizer_allocator_checks.h
+++ b/lib/sanitizer_common/sanitizer_allocator_checks.h
@@ -59,6 +59,12 @@ INLINE bool CheckForCallocOverflow(uptr size, uptr n) {
   return (max / size) < n;
 }
 
+// Returns true if the size passed to pvalloc overflows when rounded to the next
+// multiple of page_size.
+INLINE bool CheckForPvallocOverflow(uptr size, uptr page_size) {
+  return RoundUpTo(size, page_size) < size;
+}
+
 } // namespace __sanitizer
 
 #endif  // SANITIZER_ALLOCATOR_CHECKS_H