[PATCH] D53789: [hwasan] optionally right-align heap allocations
Dmitry Vyukov via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Oct 29 13:39:46 PDT 2018
dvyukov added inline comments.
================
Comment at: lib/hwasan/hwasan_allocator.cc:136
+ if (orig_size % kShadowAlignment) {
+ if (int malloc_align_right = flags()->malloc_align_right) {
----------------
eugenis wrote:
> dvyukov wrote:
> > Shouldn't we also look at user-requested alignment here? It looks like we only satisfy natural alignment.
> Yeah, at least for calls like posix_memalign.
>
> This mode will break some things anyway, ex.:
> struct S {
> int count;
> char name[0];
> };
>
> When allocated with malloc(sizeof(S) + count) the size will not be a multiple of alignment, so "count" will be misaligned. That's why this mode can not be on by default. Let's hope it is not a common case.
>
Why will not respecting alignment argument help? That's the alignment that we ensure in normal mode.
Repository:
rCRT Compiler Runtime
https://reviews.llvm.org/D53789
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