commit 4883be70a79ca5e5a7ab838ea3d506b0ee080cb5
author Peter Collingbourne <peter@pcc.me.uk> Thu Feb 11 16:16:51 2021 -0800
committer Copybara-Service <copybara-worker@google.com> Fri Feb 19 01:09:05 2021 -0800
tree 560f4f455f264e8d3eb2e4d58783d415e61b9655
parent 96344a516c78f1b12c1827f2b9fa4256ebd3329e

libunwind: Don't attempt to authenticate a null return address.

Null return addresses can appear at the bottom of the stack (i.e. the
frame corresponding to the entry point). Authenticating these addresses
will set the error code in the address, which will lead to a segfault
in the sigreturn trampoline detection code. Fix this problem by not
authenticating null addresses.

Differential Revision: https://reviews.llvm.org/D96560

GitOrigin-RevId: cddc53ef088b68586094c9841a76b41bee3994a4