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Fix insanely large stack_allocation in log_credential_status 

I'm not one to insist on C's miserly stack limits, but allocating a
256K array on the stack is too much even for me.

Bugfix on 0.2.1.7-alpha.  Found by coverity.  Fixes CID # 450.
This commit is contained in:
Nick Mathewson 2011-07-01 12:36:33 -04:00
parent 010b8dd4f6
commit d25feadebb
2 changed files with 19 additions and 2 deletions
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5
changes/cid_450 Normal file
View File

@ -0,0 +1,5 @@
o Minor bugfixes:
- Don't stack-allocate the list of supplementary GIDs when we're
about to log them. Stack-allocating NGROUPS_MAX gid_t elements
could take up to 256K, which is way too much stack. Found by
Coverity; CID #450. Bugfix on 0.2.1.7-alpha.

16
src/common/compat.c
View File

@ -1080,7 +1080,8 @@ log_credential_status(void)
/* Read, effective and saved GIDs */
gid_t rgid, egid, sgid;
/* Supplementary groups */
gid_t sup_gids[NGROUPS_MAX + 1];
gid_t *sup_gids = NULL;
int sup_gids_size;
/* Number of supplementary groups */
int ngids;
@ -1126,9 +1127,19 @@ log_credential_status(void)
#endif
/* log supplementary groups */
if ((ngids = getgroups(NGROUPS_MAX + 1, sup_gids)) < 0) {
sup_gids_size = 64;
sup_gids = tor_malloc(sizeof(gid_t) * 64);
while ((ngids = getgroups(sup_gids_size, sup_gids)) < 0 &&
errno == EINVAL &&
sup_gids_size < NGROUPS_MAX) {
sup_gids_size *= 2;
sup_gids = tor_realloc(sup_gids, sizeof(gid_t) * sup_gids_size);
}
if (ngids < 0) {
log_warn(LD_GENERAL, "Error getting supplementary GIDs: %s",
strerror(errno));
tor_free(sup_gids);
return -1;
} else {
int i, retval = 0;
@ -1158,6 +1169,7 @@ log_credential_status(void)
tor_free(cp);
});
smartlist_free(elts);
tor_free(sup_gids);
return retval;
}