Fix GC_scratch_alloc and GC_get_maps invocations to prevent SEGV

(if out of memory)

* dyn_load.c (GC_register_dynamic_libraries): If GC_scratch_alloc
fails (returns null) then abort (with the appropriate message) instead
of causing SEGV.
* os_dep.c (GC_dirty_init): Likewise.
* headers.c (GC_init_headers): Report error and exit if
GC_scratch_alloc fails.
* include/private/gc_priv.h (GC_scratch_alloc): Improve comment.
* os_dep.c (GC_print_address_map): If GC_get_maps return null then
print the appropriate message (instead of passing null to GC_err_puts
thus causing SEGV).

1 files changed, 4 insertions, 0 deletions

diff --git a/headers.c b/headers.c
index 71ab29f5..47cc526e 100644
--- a/headers.c
+++ b/headers.c
@@ -196,6 +196,10 @@ GC_INNER void GC_init_headers(void)
     register unsigned i;
 
     GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
+    if (GC_all_nils == NULL) {
+      GC_err_printf("Insufficient memory for GC_all_nils\n");
+      EXIT();
+    }
     BZERO(GC_all_nils, sizeof(bottom_index));
     for (i = 0; i < TOP_SZ; i++) {
         GC_top_index[i] = GC_all_nils;