path: root/ldso
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authorRich Felker <>2018-04-19 22:19:29 -0400
committerRich Felker <>2018-04-19 22:22:11 -0400
commitb4b1e10364c8737a632be61582e05a8d3acf5690 (patch)
tree68c07893e646a5e94c47afb7f8b01317c143968b /ldso
parent72141795d4edd17f88da192447395a48444afa10 (diff)
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.
Diffstat (limited to 'ldso')
1 files changed, 9 insertions, 0 deletions
diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index 63e7b81f..cea5f452 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -134,6 +134,9 @@ static struct dso *const nodeps_dummy;
struct debug *_dl_debug_addr = &debug;
+extern int __malloc_replaced;
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. */