Re: libpq: fix unlikely memory leak

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Neil Conway <neilc(at)samurai(dot)com>
Cc: pgsql-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: libpq: fix unlikely memory leak
Date: 2005-06-29 14:48:21
Message-ID: 9344.1120056501@sss.pgh.pa.us
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Neil Conway <neilc(at)samurai(dot)com> writes:
> The attached patch fixes a theoretical memory leak in libpq: if the
> second malloc() fails due to OOM, the memory returned by the first
> (successful) malloc() will be leaked.

Since both allocations are only transient within this routine, there's
a simpler more effective solution, which is to only do one malloc in
the first place:

char *crypt_pwd2;

/* need enough space for 2 MD5 hashes */
if (!(crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1))))
{
fprintf(stderr, libpq_gettext("out of memory\n"));
return STATUS_ERROR;
}
crypt_pwd2 = crypt_pwd + (MD5_PASSWD_LEN + 1);

and drop the free(crypt_pwd2) calls.

regards, tom lane

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