[PATCH] D81346: [KernelAddressSanitizer] Ensure global array size remains multiple of type-size

[Marco Elver via Phabricator via cfe-commits]

melver created this revision.
melver added reviewers: nathanchance, glider, andreyknvl.
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The kernel expects certain global arrays' size to remain a multiple of
the array type. In particular, for kernel modules some arrays of structs
shared with userspace are sanity-checked by modpost to have a size that
is a multiple of that type:

https://elixir.bootlin.com/linux/latest/source/scripts/mod/file2alias.c#L132

Since the AddressSanitizer takes a global and replaces it with a new one
that has the redzone appended to it, any information about the global as
well as the section size is increased. Therefore, to ensure we retain
the array-size-property required for globals, calculate the redzone size
to be a multiple of the original global's size.

To improve readability, the existing redzone size calculation is
refactored into its own function; no other functional change intended.

Report: https://github.com/ClangBuiltLinux/linux/issues/1045


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D81346

Files:
  clang/test/CodeGen/asan-globals.cpp
  llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

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