[asan] Add full redzone after every stack variable

[waltl]

Summary

We were not doing that for large shadow granularity.

[waltl]

Add full redzone after every stack variable

[vitalybuka]

llvm/unittests/Transforms/Utils/ASanStackFrameLayoutTest.cpp

73

maybe more cases with unusual granularity?

[waltl]

Add more stack frame layout tests for large shadow granularity

[waltl]

Trivial format fixes

compiler-rt/lib/asan/asan_errors.cc

if (access_size) {
     // Determine the error type.
     bug_descr = "unknown-crash";
     if (AddrIsInMem(addr)) {
       u8 *shadow_addr = (u8 *)MemToShadow(addr);
       // If we are accessing 16 bytes, look at the second shadow byte.
       if (*shadow_addr == 0 && access_size > SHADOW_GRANULARITY) shadow_addr++;
       // If we are in the partial right redzone, look at the next shadow byte.
       if (*shadow_addr > 0 && *shadow_addr < 128) shadow_addr++;
+      // For large shadow granularity, skip pass all partial right redzones.
+      if (SHADOW_GRANULARITY >= 32) {
+        while (AddrIsInShadow((uptr)shadow_addr) && *shadow_addr > 0 &&
+               *shadow_addr < 128)
+          shadow_addr++;
+      }
       bool far_from_bounds = false;
       shadow_val = *shadow_addr;
       int bug_type_score = 0;
       // For use-after-frees reads are almost as bad as writes.
       int read_after_free_bonus = 0;
       switch (shadow_val) {
         case kAsanHeapLeftRedzoneMagic:
         case kAsanArrayCookieMagic:

llvm/lib/Transforms/Utils/ASanStackFrameLayout.cpp

for (size_t i = 0; i < NumVars; i++) {
     size_t Size = Vars[i].Size;
     assert((Alignment & (Alignment - 1)) == 0);
     assert(Layout.FrameAlignment >= Alignment);
     assert((Offset % Alignment) == 0);
     assert(Size > 0);
     size_t NextAlignment = IsLast ? Granularity
                    : std::max(Granularity, Vars[i + 1].Alignment);
     size_t SizeWithRedzone = VarAndRedzoneSize(Size, NextAlignment);
+    // Add a sentinel to end of stack.
+    if (IsLast && SizeWithRedzone == Granularity)
+      SizeWithRedzone += Granularity;
     Vars[i].Offset = Offset;
     Offset += SizeWithRedzone;
   }
   if (Offset % MinHeaderSize) {
     Offset += MinHeaderSize - (Offset % MinHeaderSize);
   }
   Layout.FrameSize = Offset;
   assert((Layout.FrameSize % MinHeaderSize) == 0);

llvm/unittests/Transforms/Utils/ASanStackFrameLayoutTest.cpp

#define VAR(name, size, lifetime, alignment, line)                             \
   VAR(a, 7, 0, 1, 0);
   VAR(a, 8, 8, 1, 0);
   VAR(a, 9, 0, 1, 0);
   VAR(a, 16, 16, 1, 0);
   VAR(a, 41, 9, 1, 7);
   VAR(a, 105, 103, 1, 0);
 
   TEST_LAYOUT({a1_1}, 8, 16, "1 16 1 4 a1_1", "LL1R", "LL1R");
-  TEST_LAYOUT({a1_1}, 64, 64, "1 64 1 4 a1_1", "L1", "L1");
+  TEST_LAYOUT({a1_1}, 64, 64, "1 64 1 4 a1_1", "L1R", "L1R");
   TEST_LAYOUT({p1_32}, 8, 32, "1 32 1 8 p1_32:15", "LLLL1RRR", "LLLL1RRR");
   TEST_LAYOUT({p1_32}, 8, 64, "1 64 1 8 p1_32:15", "LLLLLLLL1RRRRRRR",
               "LLLLLLLL1RRRRRRR");
 
   TEST_LAYOUT({a1_1}, 8, 32, "1 32 1 4 a1_1", "LLLL1RRR", "LLLL1RRR");
   TEST_LAYOUT({a2_1}, 8, 32, "1 32 2 4 a2_1", "LLLL2RRR", "LLLL2RRR");
   TEST_LAYOUT({a3_1}, 8, 32, "1 32 3 4 a3_1", "LLLL3RRR", "LLLL3RRR");
   TEST_LAYOUT({a4_1}, 8, 32, "1 32 4 4 a4_1", "LLLL4RRR", "LLLL4RRR");