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Tom Lane 0e87dfe464 Harden memory context allocators against bogus chunk pointers. ... Before commit c6e0fe1f2, functions such as AllocSetFree could pretty safely presume that they were given a valid chunk pointer for their own type of context, because the indirect call through a memory context object and method struct would be very unlikely to work otherwise. But now, if pfree() is mistakenly invoked on a pointer to garbage, we have three chances in eight of ending up at one of these functions. That means we need to take extra measures to verify that we are looking at what we're supposed to be looking at, especially in debug builds. Hence, add code to verify that the chunk's back-link to a block header leads to a memory context object that satisfies the right sort of IsA() check. This is still a bit weaker than what we did before, but for the moment assume that an IsA() check is sufficient. As a compromise between speed and safety, implement these checks as Asserts when dealing with small chunks but plain test-and-elogs when dealing with large (external) chunks. The latter case should not be too performance-critical, but the former case probably is. In slab.c, all chunks are small; but nonetheless use a plain test in SlabRealloc, because that is certainly not performance-critical, indeed we should be suspicious that it's being called in error. In aset.c, additionally add some assertions that the "value" field of the chunk header is within the small range allowed for freelist indexes. Without that, we might find ourselves trying to wipe most of memory when CLOBBER_FREED_MEMORY is enabled, or scribbling on a "freelist header" that's far away from the context object. Eventually, field experience might show us that it's smarter for these tests to be active always, but for now we'll try to get away with just having them as assertions. While at it, also be more uniform about asserting that context objects passed as parameters are of the type we expect. Some places missed that altogether, and slab.c was for no very good reason doing it differently from the other allocators. Discussion: https://postgr.es/m/3578387.1665244345@sss.pgh.pa.us		3 years ago
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backend	Harden memory context allocators against bogus chunk pointers.	3 years ago
bin	meson: Add support for building with precompiled headers	3 years ago
common	meson: Add support for building with precompiled headers	3 years ago
fe_utils	meson: Add support for building with precompiled headers	3 years ago
include	Simplify our Assert infrastructure a little.	3 years ago
interfaces	Remove unnecessary uses of Abs()	3 years ago
makefiles	autoconf: Rely on ar supporting index creation	3 years ago
pl	meson: Add support for building with precompiled headers	3 years ago
port	meson: Add support for building with precompiled headers	3 years ago
template	Move darwin sysroot determination into separate file	3 years ago
test	Fix self-referencing foreign keys with partitioned tables	3 years ago
timezone	meson: Add windows resource files	3 years ago
tools	windows: Adjust FD_SETSIZE via commandline define	3 years ago
tutorial	Update copyright for 2022	4 years ago
.gitignore	…
DEVELOPERS	…
Makefile	…
Makefile.global.in	autoconf: Rely on ar supporting index creation	3 years ago
Makefile.shlib	autoconf: Rely on ar supporting index creation	3 years ago
meson.build	meson: Add initial version of meson based build system	3 years ago
nls-global.mk	Fix for make unportability	4 years ago