musl/src/internal/malloc_impl.h, branch v1.1.20 musl - an implementation of the standard library for Linux-based systems reintroduce hardening against partially-replaced allocator 2018-04-20T02:22:11+00:00 Rich Felker dalias@aerifal.cx 2018-04-20T02:19:29+00:00 b4b1e10364c8737a632be61582e05a8d3acf5690 commit 618b18c78e33acfe54a4434e91aa57b8e171df89 removed the previous detection and hardening since it was incorrect. commit 72141795d4edd17f88da192447395a48444afa10 already handled all that remained for hardening the static-linked case. in the dynamic-linked case, have the dynamic linker check whether malloc was replaced and make that information available. with these changes, the properties documented in commit c9f415d7ea2dace5bf77f6518b6afc36bb7a5732 are restored: if calloc is not provided, it will behave as malloc+memset, and any of the memalign-family functions not provided will fail with ENOMEM. 
commit 618b18c78e33acfe54a4434e91aa57b8e171df89 removed the previous
detection and hardening since it was incorrect. commit
72141795d4edd17f88da192447395a48444afa10 already handled all that
remained for hardening the static-linked case. in the dynamic-linked
case, have the dynamic linker check whether malloc was replaced and
make that information available.

with these changes, the properties documented in commit
c9f415d7ea2dace5bf77f6518b6afc36bb7a5732 are restored: if calloc is
not provided, it will behave as malloc+memset, and any of the
memalign-family functions not provided will fail with ENOMEM.
return chunks split off by memalign using __bin_chunk instead of free 2018-04-20T00:56:26+00:00 Rich Felker dalias@aerifal.cx 2018-04-20T00:56:26+00:00 72141795d4edd17f88da192447395a48444afa10 this change serves multiple purposes: 1. it ensures that static linking of memalign-family functions will pull in the system malloc implementation, thereby causing link errors if an attempt is made to link the system memalign functions with a replacement malloc (incomplete allocator replacement). 2. it eliminates calls to free that are unpaired with allocations, which are confusing when setting breakpoints or tracing execution. as a bonus, making __bin_chunk external may discourage aggressive and unnecessary inlining of it. 
this change serves multiple purposes:

1. it ensures that static linking of memalign-family functions will
pull in the system malloc implementation, thereby causing link errors
if an attempt is made to link the system memalign functions with a
replacement malloc (incomplete allocator replacement).

2. it eliminates calls to free that are unpaired with allocations,
which are confusing when setting breakpoints or tracing execution.

as a bonus, making __bin_chunk external may discourage aggressive and
unnecessary inlining of it.
move malloc implementation types and macros to an internal header 2018-04-19T22:44:17+00:00 Rich Felker dalias@aerifal.cx 2018-04-19T22:43:05+00:00 23389b1988b061e8487c316893a8a8eb77770a2f