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Merge branch 'bug20081'

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This commit is contained in:
Nick Mathewson 2016-09-14 10:17:04 -04:00
commit 4f4e995d42
4 changed files with 32 additions and 1 deletions
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5
changes/bug20081 Normal file
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@ -0,0 +1,5 @@
o Minor bugfixes (allocation):
- Change how we allocate memory for large chunks on buffers, to avoid
a (currently impossible) integer overflow, and to waste less space
when allocating unusually large chunks. Fixes bug 20081; bugfix on
0.2.0.16-alpha. Issue identified by Guido Vranken.

5
src/or/buffers.c
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@ -166,9 +166,12 @@ chunk_grow(chunk_t *chunk, size_t sz)
/** Return the allocation size we'd like to use to hold <b>target</b>
* bytes. */
static inline size_t
STATIC size_t
preferred_chunk_size(size_t target)
{
tor_assert(target <= SIZE_T_CEILING - CHUNK_HEADER_LEN);
if (CHUNK_ALLOC_SIZE(target) >= MAX_CHUNK_ALLOC)
return CHUNK_ALLOC_SIZE(target);
size_t sz = MIN_CHUNK_ALLOC;
while (CHUNK_SIZE_WITH_ALLOC(sz) < target) {
sz <<= 1;

1
src/or/buffers.h
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@ -65,6 +65,7 @@ void assert_buf_ok(buf_t *buf);
STATIC int buf_find_string_offset(const buf_t *buf, const char *s, size_t n);
STATIC void buf_pullup(buf_t *buf, size_t bytes);
void buf_get_first_chunk_data(const buf_t *buf, const char **cp, size_t *sz);
STATIC size_t preferred_chunk_size(size_t target);
#define DEBUG_CHUNK_ALLOC
/** A single chunk on a buffer. */

22
src/test/test_buffers.c
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@ -744,6 +744,27 @@ test_buffers_tls_read_mocked(void *arg)
buf_free(buf);
}
static void
test_buffers_chunk_size(void *arg)
{
(void)arg;
const int min = 256;
const int max = 65536;
tt_uint_op(preferred_chunk_size(3), OP_EQ, min);
tt_uint_op(preferred_chunk_size(25), OP_EQ, min);
tt_uint_op(preferred_chunk_size(0), OP_EQ, min);
tt_uint_op(preferred_chunk_size(256), OP_EQ, 512);
tt_uint_op(preferred_chunk_size(65400), OP_EQ, max);
/* Here, we're implicitly saying that the chunk header overhead is
* between 1 and 100 bytes. 24..48 would probably be more accurate. */
tt_uint_op(preferred_chunk_size(65536), OP_GT, 65536);
tt_uint_op(preferred_chunk_size(65536), OP_LT, 65536+100);
tt_uint_op(preferred_chunk_size(165536), OP_GT, 165536);
tt_uint_op(preferred_chunk_size(165536), OP_LT, 165536+100);
done:
;
}
struct testcase_t buffer_tests[] = {
{ "basic", test_buffers_basic, TT_FORK, NULL, NULL },
{ "copy", test_buffer_copy, TT_FORK, NULL, NULL },
@ -758,6 +779,7 @@ struct testcase_t buffer_tests[] = {
NULL, NULL},
{ "tls_read_mocked", test_buffers_tls_read_mocked, 0,
NULL, NULL },
{ "chunk_size", test_buffers_chunk_size, 0, NULL, NULL },
END_OF_TESTCASES
};