The broker attempts to use sbrk() to allocate memory to track ptrace
attachments. If the process failed due to an OOM, this system call might
fail, the broker falls back to saving attachments on the stack, and then
overruns the stack.
This change updates the broker to use sys_mmap() instead of sbrk(),
which is expected to work at least as well. If sys_mmap() fails or
the first mapped page is exhausted, further attachments fail without
attempting to save them to the stack.
Bug: chromium:1128441
Change-Id: Ibffaa986403adaf3178ee77e6d210053fbf60f26
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2488280
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
