From: Junio C Hamano <gitster@pobox.com>
To: Stefan Beller <sbeller@google.com>
Cc: Eric Sunshine <sunshine@sunshineco.com>, Git List <git@vger.kernel.org>
Subject: Re: [PATCH 1/6] path.c: allocate enough memory for string
Date: Wed, 30 Mar 2016 10:16:13 -0700 [thread overview]
Message-ID: <xmqqr3erubs2.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <CAGZ79kb6dsaSxQ+HaYODBurnFz3MbsisSNkdrckFZLvSCvS-JQ@mail.gmail.com> (Stefan Beller's message of "Wed, 30 Mar 2016 09:41:38 -0700")
Stefan Beller <sbeller@google.com> writes:
> On Tue, Mar 29, 2016 at 5:57 PM, Eric Sunshine <sunshine@sunshineco.com> wrote:
>> On Tue, Mar 29, 2016 at 8:38 PM, Stefan Beller <sbeller@google.com> wrote:
>>> `strlen` returns the length of a string without the terminating null byte.
>>> To make sure enough memory is allocated we need to pass `strlen(..) + 1`
>>> to the allocation function.
>>>
>>> Signed-off-by: Stefan Beller <sbeller@google.com>
>>> ---
>>> diff --git a/path.c b/path.c
>>> @@ -155,7 +155,7 @@ static struct trie *make_trie_node(const char *key, void *value)
>>> struct trie *new_node = xcalloc(1, sizeof(*new_node));
>>> new_node->len = strlen(key);
>>> if (new_node->len) {
>>> - new_node->contents = xmalloc(new_node->len);
>>> + new_node->contents = xmalloc(new_node->len + 1);
>>> memcpy(new_node->contents, key, new_node->len);
>>
>> Huh? This is a trie. It never accesses 'contents' as a NUL-terminated
>> string. Plus, no NUL is ever even copied, thus this is just
>> overallocating. How is this an improvement?
>
> By using strlen, I assumed it was a standard C string.
> I missed that, though.
You took hint from a wrong place. You are auditing the destination
buffer, so the correct place to take hint from is the memcpy() that
touches the destination.
next prev parent reply other threads:[~2016-03-30 17:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-30 0:38 [PATCH 0/6] Some cleanups Stefan Beller
2016-03-30 0:38 ` [PATCH 1/6] path.c: allocate enough memory for string Stefan Beller
2016-03-30 0:56 ` Junio C Hamano
2016-03-30 0:57 ` Eric Sunshine
2016-03-30 16:41 ` Stefan Beller
2016-03-30 17:16 ` Junio C Hamano [this message]
2016-03-30 0:38 ` [PATCH 2/6] imap-send.c, cram: allocate enough memory for null terminated string Stefan Beller
2016-03-30 1:02 ` Eric Sunshine
2016-03-30 1:07 ` Jeff King
2016-03-30 0:38 ` [PATCH 3/6] notes: don't leak memory in git_config_get_notes_strategy Stefan Beller
2016-03-30 1:11 ` Eric Sunshine
2016-03-30 1:13 ` Jeff King
2016-03-30 17:17 ` Junio C Hamano
2016-03-30 0:38 ` [PATCH 4/6] abbrev_sha1_in_line: don't leak memory Stefan Beller
2016-03-30 1:11 ` Jeff King
2016-03-30 1:30 ` Eric Sunshine
2016-03-30 1:31 ` Jeff King
2016-03-30 17:06 ` Junio C Hamano
2016-03-30 17:21 ` Jeff King
2016-03-30 0:38 ` [PATCH 5/6] bundle: don't leak an fd in case of early return Stefan Beller
2016-03-30 1:17 ` Jeff King
2016-03-30 17:19 ` Junio C Hamano
2016-03-30 0:38 ` [PATCH 6/6] credential-cache, send_request: close fd when done Stefan Beller
2016-03-30 1:20 ` Jeff King
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