From b4b1e10364c8737a632be61582e05a8d3acf5690 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 19 Apr 2018 22:19:29 -0400 Subject: reintroduce hardening against partially-replaced allocator 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. --- ldso/dynlink.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'ldso') diff --git a/ldso/dynlink.c b/ldso/dynlink.c index 63e7b81f..cea5f452 100644 --- a/ldso/dynlink.c +++ b/ldso/dynlink.c @@ -133,6 +133,9 @@ static struct dso *const nodeps_dummy; struct debug *_dl_debug_addr = &debug; +__attribute__((__visibility__("hidden"))) +extern int __malloc_replaced; + __attribute__((__visibility__("hidden"))) void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0; @@ -1691,6 +1694,12 @@ _Noreturn void __dls3(size_t *sp) if (ldso_fail) _exit(127); if (ldd_mode) _exit(0); + /* Determine if malloc was interposed by a replacement implementation + * so that calloc and the memalign family can harden against the + * possibility of incomplete replacement. */ + if (find_sym(head, "malloc", 1).dso != &ldso) + __malloc_replaced = 1; + /* Switch to runtime mode: any further failures in the dynamic * linker are a reportable failure rather than a fatal startup * error. */ -- cgit v1.2.1