[PATCH] D126343: [libunwind] Use process_vm_readv to avoid potential segfaults

[Matt Denton via Phabricator via llvm-commits]

mpdenton added a comment.

The Chrome sandbox disallows process_vm_readv() (I think most seccomp sandboxes would) so this causes crashes when trying to collect backtraces at runtime.

What would happen if I caused process_vm_read() to return EPERM here? Would the unwinder still be able to unwind past the sigreturn trampoline with heuristics?

If not, is it possible to introduce a fallback that reads from the address directly, or possibly uses mincore() to check if the address is valid (a small race is possible)?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D126343/new/

https://reviews.llvm.org/D126343