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Make sure we don't read or write past the end of the group buffer.

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We need to leave room for the terminating NULL in gr_mem.
It is possible for gbm->numgids > gbm->maxgids if we ran out of room.
This commit is contained in:
Todd C. Miller 2021-06-07 13:08:10 -06:00
parent 4b73c98c06
commit 3104d8ba0b
1 changed files with 6 additions and 4 deletions
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10
lib/util/getgrouplist.c
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@ -270,9 +270,9 @@ str2grp(const char *instr, int inlen, void *ent, char *buf, int buflen)
grp->gr_mem = NULL; grp->gr_mem = NULL;
if (*fieldsep != '\0') { if (*fieldsep != '\0') {
grp->gr_mem = gr_mem = (char **)ALIGN(buf + inlen + 1); grp->gr_mem = gr_mem = (char **)ALIGN(buf + inlen + 1);
gr_end = (char **)((unsigned long)(buf + buflen) & ~ALIGNBYTES); gr_end = (char **)((unsigned long)(buf + buflen) & ~ALIGNBYTES) - 1;
for (;;) { for (;;) {
if (gr_mem == gr_end) if (gr_mem >= gr_end)
debug_return_int(NSS_STR_PARSE_ERANGE); /* out of space! */ debug_return_int(NSS_STR_PARSE_ERANGE); /* out of space! */
*gr_mem++ = cp; *gr_mem++ = cp;
if (fieldsep == NULL) if (fieldsep == NULL)
@ -311,13 +311,15 @@ process_cstr(const char *instr, int inlen, struct nss_groupsbymem *gbm,
/* Parse groups file string -> struct group. */ /* Parse groups file string -> struct group. */
grp = buf->result; grp = buf->result;
error = (*gbm->str2ent)(instr, inlen, grp, buf->buffer, buf->buflen); error = (*gbm->str2ent)(instr, inlen, grp, buf->buffer, buf->buflen);
if (error || grp->gr_mem == NULL) if (error != NSS_STR_PARSE_SUCCESS || grp->gr_mem == NULL)
goto done; goto done;
for (gr_mem = grp->gr_mem; *gr_mem != NULL; gr_mem++) { for (gr_mem = grp->gr_mem; *gr_mem != NULL; gr_mem++) {
if (strcmp(*gr_mem, user) == 0) { if (strcmp(*gr_mem, user) == 0) {
const int numgids = MIN(gbm->numgids, gbm->maxgids);
/* Append to gid_array unless gr_gid is a dupe. */ /* Append to gid_array unless gr_gid is a dupe. */
for (i = 0; i < gbm->numgids; i++) { for (i = 0; i < numgids; i++) {
if (gbm->gid_array[i] == grp->gr_gid) if (gbm->gid_array[i] == grp->gr_gid)
goto done; /* already present */ goto done; /* already present */
} }