[compiler-rt] [asan] Fix `unknown-crash` reported for multi-byte errors (PR #144480)

[Vitaly Buka via llvm-commits]

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@@ -437,8 +437,11 @@ ErrorGeneric::ErrorGeneric(u32 tid, uptr pc_, uptr bp_, uptr sp_, uptr addr,
     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 > ASAN_SHADOW_GRANULARITY)
+      u8 *shadow_addr_upper_bound =
+          shadow_addr + (1 + ((access_size - 1) / ASAN_SHADOW_GRANULARITY));
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vitalybuka wrote:

`shadow_addr_upper_bound = (u8 *)MemToShadow(addr + access_size)`?

https://github.com/llvm/llvm-project/pull/144480