[ruby-core:30953] st.c: avoid 2 of 3 NULL-dereference bugs in sym-tab initialization

Author: Jim Meyering
ruby -v: ruby 1.9.3dev (2010-06-29 trunk 28473) [x86_64-linux]

Here is a patch to fix two NULL-dereference problems in st.c's
st_init_table_with_size function.  Its malloc and calloc return
values were not checked for NULL.

However, there is another problem not fixed by the patch below.
The ADD_DIRECT macro calls "alloc" (aka malloc), and
immediately dereferences the result.  A minimal patch
would be to use xmalloc in place of alloc here, but
I don't know if such semantics would be appropriate.


#define ADD_DIRECT(table, key, value, hash_val, bin_pos)\
do {\
    st_table_entry *entry;\
    if (table->num_entries > ST_DEFAULT_MAX_DENSITY * table->num_bins) {\
	rehash(table);\
        bin_pos = hash_val % table->num_bins;\
    }\
    \
    entry = alloc(st_table_entry);\
    \
    entry->hash = hash_val;\
    ...

Tue Jun 29 15:04:38 2010  Jim Meyering  <[e-mail]>

	st.c: do not dereference NULL upon allocation failure
	* st.c (st_init_table_with_size): Handle NULL-return from calloc
	and malloc.

From a0803a034b2cc26748eed586afbdae27651ccdcb Mon Sep 17 00:00:00 2001
From: Jim Meyering <[e-mail]>
Date: Tue, 29 Jun 2010 08:06:10 +0200
Subject: [PATCH] st.c: do not dereference NULL upon allocation failure

* st.c (st_init_table_with_size): Handle NULL-return from calloc
and malloc.
---
 st.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/st.c b/st.c
index ec518e9..47b0f2f 100644
--- a/st.c
+++ b/st.c
@@ -184,11 +184,17 @@ st_init_table_with_size(const struct st_hash_type *type, st_index_t size)
     size = new_size(size);	/* round up to prime number */

     tbl = alloc(st_table);
+    if (tbl == NULL)
+      return NULL;
     tbl->type = type;
     tbl->num_entries = 0;
     tbl->entries_packed = type == &type_numhash && size/2 <= MAX_PACKED_NUMHASH;
     tbl->num_bins = size;
     tbl->bins = (st_table_entry **)Calloc(size, sizeof(st_table_entry*));
+    if (!tbl->bins) {
+	free (tbl);
+	return NULL;
+    }
     tbl->head = 0;
     tbl->tail = 0;

--
1.7.2.rc0.206.g3336