[PATCH] D70762: scudo: Add initial memory tagging support.

[Mitch Phillips via Phabricator via llvm-commits]

hctim added a comment.

> The granules
>  either side of the allocation are tagged with tag 0, which is normally
>  excluded from the set of tags that may be selected randomly

It seems valuable to have the LHS and RHS of an allocation as a nonzero tag. IIUC, the chunk header is on the LHS for primary allocations, and making the header MTE-protected (the tag can be stored in the Primary allocator struct somewhere) seems like a good additional security step to make it unwriteable from a deterministic (zeroed) pointer.



================
Comment at: compiler-rt/lib/scudo/standalone/primary64.h:193
 
+  bool useMemoryTagging() const { return SupportsMemoryTagging && UseMemoryTagging; }
+  void disableMemoryTagging() { UseMemoryTagging = false; }
----------------
Nit: line length


================
Comment at: compiler-rt/lib/scudo/standalone/primary64.h:293
     }
-
     const u32 NumberOfBlocks = Min(
----------------
nit: leave newline


Repository:
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  https://reviews.llvm.org/D70762/new/

https://reviews.llvm.org/D70762