[compiler-rt] [HWASan] symbolize stack overflows (PR #95308)

[Evgenii Stepanov via llvm-commits]

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@@ -336,16 +368,18 @@ class Symbolizer:
         size = local[4]
         if frame_offset is None or size is None:
           continue
-        obj_offset = (self.__last_access_address - fp - frame_offset) & fp_mask
-        if obj_offset >= size:
-          continue
+        obj_offset = (self.__last_access_address & fp_mask) - ((fp + frame_offset) & fp_mask)
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eugenis wrote:

why? this is very biased towards overflow and against underflow. I.e., with fp_mask of 1Mb, access at (1Mb - 8 bytes) and the object offset of 8 bytes this code will come up with obj_offset of (1Mb - 16) instead of (-8).

https://github.com/llvm/llvm-project/pull/95308