From b048a482f088e53144d26a61c390bed0210f49f2 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Thu, 25 Apr 2024 15:01:07 +0200 Subject: CVE-2024-33600: nscd: Avoid null pointer crashes after notfound response (bug 31678) The addgetnetgrentX call in addinnetgrX may have failed to produce a result, so the result variable in addinnetgrX can be NULL. Use db->negtimeout as the fallback value if there is no result data; the timeout is also overwritten below. Also avoid sending a second not-found response. (The client disconnects after receiving the first response, so the data stream did not go out of sync even without this fix.) It is still beneficial to add the negative response to the mapping, so that the client can get it from there in the future, instead of going through the socket. Reviewed-by: Siddhesh Poyarekar --- nscd/netgroupcache.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/nscd/netgroupcache.c b/nscd/netgroupcache.c index c18fe111f3..e22ffa5884 100644 --- a/nscd/netgroupcache.c +++ b/nscd/netgroupcache.c @@ -511,14 +511,15 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req, datahead_init_pos (&dataset->head, sizeof (*dataset) + req->key_len, sizeof (innetgroup_response_header), - he == NULL ? 0 : dh->nreloads + 1, result->head.ttl); + he == NULL ? 0 : dh->nreloads + 1, + result == NULL ? db->negtimeout : result->head.ttl); /* Set the notfound status and timeout based on the result from getnetgrent. */ - dataset->head.notfound = result->head.notfound; + dataset->head.notfound = result == NULL || result->head.notfound; dataset->head.timeout = timeout; dataset->resp.version = NSCD_VERSION; - dataset->resp.found = result->resp.found; + dataset->resp.found = result != NULL && result->resp.found; /* Until we find a matching entry the result is 0. */ dataset->resp.result = 0; @@ -566,7 +567,9 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req, goto out; } - if (he == NULL) + /* addgetnetgrentX may have already sent a notfound response. Do + not send another one. */ + if (he == NULL && dataset->resp.found) { /* We write the dataset before inserting it to the database since while inserting this thread might block and so would -- cgit 1.4.1