tree b1102373d46526285b7edfd5c074dc48fafb8597
parent f13322ede1e4824e20fb871dabd22e91dcc8ab0a
author Willy Tarreau <w@1wt.eu> 1511362049 +0100
committer Willy Tarreau <w@1wt.eu> 1511376237 +0100
encoding latin1

MINOR: pools: implement DEBUG_UAF to detect use after free

This code has been used successfully a few times in the past to detect
that a pool was used after being freed. Its main goal is to allocate a
full page for each object so that they are always released individually
and unmapped from memory. This way if any part of the code reference the
object after is was freed and before it is reallocated, a segv occurs at
the exact offending location. It does a few extra things such as writing
to the memory area before freeing to detect double-frees and free of
read-only areas, and placing the data at the end of the page instead of
the beginning so that out of bounds accesses are easier to spot. The
amount of memory used with this is huge (about 10 times the regular
usage) but it can be useful sometimes.