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nscd: Fix use-after-free in addgetnetgrentX [BZ #23520]

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addinnetgrX may use the heap-allocated buffer, so free the buffer
in this function.

(cherry picked from commit 745664bd79)
This commit is contained in:
Florian Weimer 2018-08-28 13:19:27 +02:00 committed by Carlos O'Donell
parent 53a7e59405
commit 7d174f5353
2 changed files with 41 additions and 13 deletions
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12
ChangeLog
View File

@ -1,3 +1,15 @@
2018-08-28 Florian Weimer <fweimer@redhat.com>
[BZ #23520]
nscd: Fix use-after-free in addgetnetgrentX and its callers.
* nscd/netgroupcache.c
(addgetnetgrentX): Add tofreep parameter. Do not free
heap-allocated buffer.
(addinnetgrX): Free buffer allocated bt addgetnetgrentX.
(addgetnetgrentX_ignore): New function.
(addgetnetgrent): Call it.
(readdgetnetgrent): Likewise.
2018-08-16 DJ Delorie <dj@delorie.com>
* malloc/malloc.c (_int_free): Check for corrupt prev_size vs size.

42
nscd/netgroupcache.c
View File

@ -113,7 +113,8 @@ do_notfound (struct database_dyn *db, int fd, request_header *req,
static time_t
addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
const char *key, uid_t uid, struct hashentry *he,
struct datahead *dh, struct dataset **resultp)
struct datahead *dh, struct dataset **resultp,
void **tofreep)
{
if (__glibc_unlikely (debug_level > 0))
{
@ -139,6 +140,7 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
size_t group_len = strlen (key) + 1;
struct name_list *first_needed
= alloca (sizeof (struct name_list) + group_len);
*tofreep = NULL;
if (netgroup_database == NULL
&& __nss_database_lookup ("netgroup", NULL, NULL, &netgroup_database))
@ -151,6 +153,7 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
memset (&data, '\0', sizeof (data));
buffer = xmalloc (buflen);
*tofreep = buffer;
first_needed->next = first_needed;
memcpy (first_needed->name, key, group_len);
data.needed_groups = first_needed;
@ -439,8 +442,6 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
}
out:
free (buffer);
*resultp = dataset;
return timeout;
@ -477,8 +478,12 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req,
group, group_len,
db, uid);
time_t timeout;
void *tofree;
if (result != NULL)
timeout = result->head.timeout;
{
timeout = result->head.timeout;
tofree = NULL;
}
else
{
request_header req_get =
@ -487,7 +492,7 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req,
.key_len = group_len
};
timeout = addgetnetgrentX (db, -1, &req_get, group, uid, NULL, NULL,
&result);
&result, &tofree);
}
struct indataset
@ -560,7 +565,7 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req,
++dh->nreloads;
if (cacheable)
pthread_rwlock_unlock (&db->lock);
return timeout;
goto out;
}
if (he == NULL)
@ -596,17 +601,30 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req,
dh->usable = false;
}
out:
free (tofree);
return timeout;
}
static time_t
addgetnetgrentX_ignore (struct database_dyn *db, int fd, request_header *req,
const char *key, uid_t uid, struct hashentry *he,
struct datahead *dh)
{
struct dataset *ignore;
void *tofree;
time_t timeout = addgetnetgrentX (db, fd, req, key, uid, he, dh,
&ignore, &tofree);
free (tofree);
return timeout;
}
void
addgetnetgrent (struct database_dyn *db, int fd, request_header *req,
void *key, uid_t uid)
{
struct dataset *ignore;
addgetnetgrentX (db, fd, req, key, uid, NULL, NULL, &ignore);
addgetnetgrentX_ignore (db, fd, req, key, uid, NULL, NULL);
}
@ -619,10 +637,8 @@ readdgetnetgrent (struct database_dyn *db, struct hashentry *he,
.type = GETNETGRENT,
.key_len = he->len
};
struct dataset *ignore;
return addgetnetgrentX (db, -1, &req, db->data + he->key, he->owner, he, dh,
&ignore);
return addgetnetgrentX_ignore
(db, -1, &req, db->data + he->key, he->owner, he, dh);
}