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Properly fix memory leak in _nss_dns_gethostbyname4_r with big DNS answer

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Instead of trying to guess whether the second buffer needs to be freed
set a flag at the place it is allocated
This commit is contained in:
Andreas Schwab
2014-02-18 10:57:25 +01:00
parent c6af2d896c
commit ab09bf616a
8 changed files with 95 additions and 49 deletions
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45
resolv/res_query.c
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@ -98,7 +98,7 @@ static int
__libc_res_nquerydomain(res_state statp, const char *name, const char *domain,
int class, int type, u_char *answer, int anslen,
u_char **answerp, u_char **answerp2, int *nanswerp2,
int *resplen2);
int *resplen2, int *answerp2_malloced);
/*
* Formulate a normal query, send, and await answer.
@ -119,7 +119,8 @@ __libc_res_nquery(res_state statp,
u_char **answerp, /* if buffer needs to be enlarged */
u_char **answerp2,
int *nanswerp2,
int *resplen2)
int *resplen2,
int *answerp2_malloced)
{
HEADER *hp = (HEADER *) answer;
HEADER *hp2;
@ -224,7 +225,8 @@ __libc_res_nquery(res_state statp,
}
assert (answerp == NULL || (void *) *answerp == (void *) answer);
n = __libc_res_nsend(statp, query1, nquery1, query2, nquery2, answer,
anslen, answerp, answerp2, nanswerp2, resplen2);
anslen, answerp, answerp2, nanswerp2, resplen2,
answerp2_malloced);
if (use_malloc)
free (buf);
if (n < 0) {
@ -316,7 +318,7 @@ res_nquery(res_state statp,
int anslen) /* size of answer buffer */
{
return __libc_res_nquery(statp, name, class, type, answer, anslen,
NULL, NULL, NULL, NULL);
NULL, NULL, NULL, NULL, NULL);
}
libresolv_hidden_def (res_nquery)
@ -335,7 +337,8 @@ __libc_res_nsearch(res_state statp,
u_char **answerp,
u_char **answerp2,
int *nanswerp2,
int *resplen2)
int *resplen2,
int *answerp2_malloced)
{
const char *cp, * const *domain;
HEADER *hp = (HEADER *) answer;
@ -360,7 +363,7 @@ __libc_res_nsearch(res_state statp,
if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
return (__libc_res_nquery(statp, cp, class, type, answer,
anslen, answerp, answerp2,
nanswerp2, resplen2));
nanswerp2, resplen2, answerp2_malloced));
#ifdef DEBUG
if (statp->options & RES_DEBUG)
@ -377,7 +380,8 @@ __libc_res_nsearch(res_state statp,
if (dots >= statp->ndots || trailing_dot) {
ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
answer, anslen, answerp,
answerp2, nanswerp2, resplen2);
answerp2, nanswerp2, resplen2,
answerp2_malloced);
if (ret > 0 || trailing_dot)
return (ret);
saved_herrno = h_errno;
@ -386,11 +390,11 @@ __libc_res_nsearch(res_state statp,
answer = *answerp;
anslen = MAXPACKET;
}
if (answerp2
&& (*answerp2 < answer || *answerp2 >= answer + anslen))
if (answerp2 && *answerp2_malloced)
{
free (*answerp2);
*answerp2 = NULL;
*answerp2_malloced = 0;
}
}
@ -417,7 +421,7 @@ __libc_res_nsearch(res_state statp,
class, type,
answer, anslen, answerp,
answerp2, nanswerp2,
resplen2);
resplen2, answerp2_malloced);
if (ret > 0)
return (ret);
@ -425,12 +429,11 @@ __libc_res_nsearch(res_state statp,
answer = *answerp;
anslen = MAXPACKET;
}
if (answerp2
&& (*answerp2 < answer
|| *answerp2 >= answer + anslen))
if (answerp2 && *answerp2_malloced)
{
free (*answerp2);
*answerp2 = NULL;
*answerp2_malloced = 0;
}
/*
@ -486,7 +489,8 @@ __libc_res_nsearch(res_state statp,
&& !(tried_as_is || root_on_list)) {
ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
answer, anslen, answerp,
answerp2, nanswerp2, resplen2);
answerp2, nanswerp2, resplen2,
answerp2_malloced);
if (ret > 0)
return (ret);
}
@ -498,10 +502,11 @@ __libc_res_nsearch(res_state statp,
* else send back meaningless H_ERRNO, that being the one from
* the last DNSRCH we did.
*/
if (answerp2 && (*answerp2 < answer || *answerp2 >= answer + anslen))
if (answerp2 && *answerp2_malloced)
{
free (*answerp2);
*answerp2 = NULL;
*answerp2_malloced = 0;
}
if (saved_herrno != -1)
RES_SET_H_ERRNO(statp, saved_herrno);
@ -521,7 +526,7 @@ res_nsearch(res_state statp,
int anslen) /* size of answer */
{
return __libc_res_nsearch(statp, name, class, type, answer,
anslen, NULL, NULL, NULL, NULL);
anslen, NULL, NULL, NULL, NULL, NULL);
}
libresolv_hidden_def (res_nsearch)
@ -539,7 +544,8 @@ __libc_res_nquerydomain(res_state statp,
u_char **answerp,
u_char **answerp2,
int *nanswerp2,
int *resplen2)
int *resplen2,
int *answerp2_malloced)
{
char nbuf[MAXDNAME];
const char *longname = nbuf;
@ -581,7 +587,7 @@ __libc_res_nquerydomain(res_state statp,
}
return (__libc_res_nquery(statp, longname, class, type, answer,
anslen, answerp, answerp2, nanswerp2,
resplen2));
resplen2, answerp2_malloced));
}
int
@ -593,7 +599,8 @@ res_nquerydomain(res_state statp,
int anslen) /* size of answer */
{
return __libc_res_nquerydomain(statp, name, domain, class, type,
answer, anslen, NULL, NULL, NULL, NULL);
answer, anslen, NULL, NULL, NULL, NULL,
NULL);
}
libresolv_hidden_def (res_nquerydomain)