From 1263d583d2e28afb8be53f8d6922f0842036f35d Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Thu, 25 Apr 2024 15:00:45 +0200
Subject: [PATCH] CVE-2024-33599: nscd: Stack-based buffer overflow in netgroup
 cache (bug 31677)

Using alloca matches what other caches do.  The request length is
bounded by MAXKEYLEN.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit 87801a8fd06db1d654eea3e4f7626ff476a9bdaa)
---
 nscd/netgroupcache.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/nscd/netgroupcache.c b/nscd/netgroupcache.c
index 0c6e46f15c..f227dc7fa2 100644
--- a/nscd/netgroupcache.c
+++ b/nscd/netgroupcache.c
@@ -502,12 +502,13 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req,
       = (struct indataset *) mempool_alloc (db,
 					    sizeof (*dataset) + req->key_len,
 					    1);
-  struct indataset dataset_mem;
   bool cacheable = true;
   if (__glibc_unlikely (dataset == NULL))
     {
       cacheable = false;
-      dataset = &dataset_mem;
+      /* The alloca is safe because nscd_run_worker verfies that
+	 key_len is not larger than MAXKEYLEN.  */
+      dataset = alloca (sizeof (*dataset) + req->key_len);
     }
 
   datahead_init_pos (&dataset->head, sizeof (*dataset) + req->key_len,
From c99f886de54446cd4447db6b44be93dabbdc2f8b Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Thu, 25 Apr 2024 15:01:07 +0200
Subject: [PATCH] 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 <siddhesh@sourceware.org>
(cherry picked from commit b048a482f088e53144d26a61c390bed0210f49f2)
---
 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
From 5a508e0b508c8ad53bd0d2fb48fd71b242626341 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Thu, 25 Apr 2024 15:01:07 +0200
Subject: [PATCH] CVE-2024-33600: nscd: Do not send missing not-found response
 in addgetnetgrentX (bug 31678)

If we failed to add a not-found response to the cache, the dataset
point can be null, resulting in a null pointer dereference.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
(cherry picked from commit 7835b00dbce53c3c87bbbb1754a95fb5e58187aa)
---
 nscd/netgroupcache.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/nscd/netgroupcache.c b/nscd/netgroupcache.c
index f227dc7fa2..c18fe111f3 100644
--- a/nscd/netgroupcache.c
+++ b/nscd/netgroupcache.c
@@ -147,7 +147,7 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
       /* No such service.  */
       cacheable = do_notfound (db, fd, req, key, &dataset, &total, &timeout,
 			       &key_copy);
-      goto writeout;
+      goto maybe_cache_add;
     }
 
   memset (&data, '\0', sizeof (data));
@@ -348,7 +348,7 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
     {
       cacheable = do_notfound (db, fd, req, key, &dataset, &total, &timeout,
 			       &key_copy);
-      goto writeout;
+      goto maybe_cache_add;
     }
 
   total = buffilled;
@@ -410,14 +410,12 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
   }
 
   if (he == NULL && fd != -1)
-    {
-      /* We write the dataset before inserting it to the database
-	 since while inserting this thread might block and so would
-	 unnecessarily let the receiver wait.  */
-    writeout:
+    /* We write the dataset before inserting it to the database since
+       while inserting this thread might block and so would
+       unnecessarily let the receiver wait.  */
       writeall (fd, &dataset->resp, dataset->head.recsize);
-    }
 
+ maybe_cache_add:
   if (cacheable)
     {
       /* If necessary, we also propagate the data to disk.  */
From a9a8d3eebb145779a18d90e3966009a1daa63cd8 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Thu, 25 Apr 2024 15:01:07 +0200
Subject: [PATCH] CVE-2024-33601, CVE-2024-33602: nscd: netgroup: Use two
 buffers in addgetnetgrentX (bug 31680)

This avoids potential memory corruption when the underlying NSS
callback function does not use the buffer space to store all strings
(e.g., for constant strings).

Instead of custom buffer management, two scratch buffers are used.
This increases stack usage somewhat.

Scratch buffer allocation failure is handled by return -1
(an invalid timeout value) instead of terminating the process.
This fixes bug 31679.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
(cherry picked from commit c04a21e050d64a1193a6daab872bca2528bda44b)
---
 nscd/netgroupcache.c | 219 ++++++++++++++++++++++++-------------------
 1 file changed, 121 insertions(+), 98 deletions(-)

diff --git a/nscd/netgroupcache.c b/nscd/netgroupcache.c
index e22ffa5884..e8fe041846 100644
--- a/nscd/netgroupcache.c
+++ b/nscd/netgroupcache.c
@@ -23,6 +23,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/mman.h>
+#include <scratch_buffer.h>
 
 #include "../nss/netgroup.h"
 #include "nscd.h"
@@ -65,6 +66,16 @@ struct dataset
   char strdata[0];
 };
 
+/* Send a notfound response to FD.  Always returns -1 to indicate an
+   ephemeral error.  */
+static time_t
+send_notfound (int fd)
+{
+  if (fd != -1)
+    TEMP_FAILURE_RETRY (send (fd, &notfound, sizeof (notfound), MSG_NOSIGNAL));
+  return -1;
+}
+
 /* Sends a notfound message and prepares a notfound dataset to write to the
    cache.  Returns true if there was enough memory to allocate the dataset and
    returns the dataset in DATASETP, total bytes to write in TOTALP and the
@@ -83,8 +94,7 @@ do_notfound (struct database_dyn *db, int fd, request_header *req,
   total = sizeof (notfound);
   timeout = time (NULL) + db->negtimeout;
 
-  if (fd != -1)
-    TEMP_FAILURE_RETRY (send (fd, &notfound, total, MSG_NOSIGNAL));
+  send_notfound (fd);
 
   dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len, 1);
   /* If we cannot permanently store the result, so be it.  */
@@ -109,11 +119,78 @@ do_notfound (struct database_dyn *db, int fd, request_header *req,
   return cacheable;
 }
 
+struct addgetnetgrentX_scratch
+{
+  /* This is the result that the caller should use.  It can be NULL,
+     point into buffer, or it can be in the cache.  */
+  struct dataset *dataset;
+
+  struct scratch_buffer buffer;
+
+  /* Used internally in addgetnetgrentX as a staging area.  */
+  struct scratch_buffer tmp;
+
+  /* Number of bytes in buffer that are actually used.  */
+  size_t buffer_used;
+};
+
+static void
+addgetnetgrentX_scratch_init (struct addgetnetgrentX_scratch *scratch)
+{
+  scratch->dataset = NULL;
+  scratch_buffer_init (&scratch->buffer);
+  scratch_buffer_init (&scratch->tmp);
+
+  /* Reserve space for the header.  */
+  scratch->buffer_used = sizeof (struct dataset);
+  static_assert (sizeof (struct dataset) < sizeof (scratch->tmp.__space),
+		 "initial buffer space");
+  memset (scratch->tmp.data, 0, sizeof (struct dataset));
+}
+
+static void
+addgetnetgrentX_scratch_free (struct addgetnetgrentX_scratch *scratch)
+{
+  scratch_buffer_free (&scratch->buffer);
+  scratch_buffer_free (&scratch->tmp);
+}
+
+/* Copy LENGTH bytes from S into SCRATCH.  Returns NULL if SCRATCH
+   could not be resized, otherwise a pointer to the copy.  */
+static char *
+addgetnetgrentX_append_n (struct addgetnetgrentX_scratch *scratch,
+			  const char *s, size_t length)
+{
+  while (true)
+    {
+      size_t remaining = scratch->buffer.length - scratch->buffer_used;
+      if (remaining >= length)
+	break;
+      if (!scratch_buffer_grow_preserve (&scratch->buffer))
+	return NULL;
+    }
+  char *copy = scratch->buffer.data + scratch->buffer_used;
+  memcpy (copy, s, length);
+  scratch->buffer_used += length;
+  return copy;
+}
+
+/* Copy S into SCRATCH, including its null terminator.  Returns false
+   if SCRATCH could not be resized.  */
+static bool
+addgetnetgrentX_append (struct addgetnetgrentX_scratch *scratch, const char *s)
+{
+  if (s == NULL)
+    s = "";
+  return addgetnetgrentX_append_n (scratch, s, strlen (s) + 1) != NULL;
+}
+
+/* Caller must initialize and free *SCRATCH.  If the return value is
+   negative, this function has sent a notfound response.  */
 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,
-		 void **tofreep)
+		 struct datahead *dh, struct addgetnetgrentX_scratch *scratch)
 {
   if (__glibc_unlikely (debug_level > 0))
     {
@@ -132,14 +209,10 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
 
   char *key_copy = NULL;
   struct __netgrent data;
-  size_t buflen = MAX (1024, sizeof (*dataset) + req->key_len);
-  size_t buffilled = sizeof (*dataset);
-  char *buffer = NULL;
   size_t nentries = 0;
   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_get (nss_database_netgroup, &netgroup_database))
@@ -151,8 +224,6 @@ 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;
@@ -195,8 +266,8 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
 		while (1)
 		  {
 		    int e;
-		    status = getfct.f (&data, buffer + buffilled,
-				       buflen - buffilled - req->key_len, &e);
+		    status = getfct.f (&data, scratch->tmp.data,
+				       scratch->tmp.length, &e);
 		    if (status == NSS_STATUS_SUCCESS)
 		      {
 			if (data.type == triple_val)
@@ -204,68 +275,10 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
 			    const char *nhost = data.val.triple.host;
 			    const char *nuser = data.val.triple.user;
 			    const char *ndomain = data.val.triple.domain;
-
-			    size_t hostlen = strlen (nhost ?: "") + 1;
-			    size_t userlen = strlen (nuser ?: "") + 1;
-			    size_t domainlen = strlen (ndomain ?: "") + 1;
-
-			    if (nhost == NULL || nuser == NULL || ndomain == NULL
-				|| nhost > nuser || nuser > ndomain)
-			      {
-				const char *last = nhost;
-				if (last == NULL
-				    || (nuser != NULL && nuser > last))
-				  last = nuser;
-				if (last == NULL
-				    || (ndomain != NULL && ndomain > last))
-				  last = ndomain;
-
-				size_t bufused
-				  = (last == NULL
-				     ? buffilled
-				     : last + strlen (last) + 1 - buffer);
-
-				/* We have to make temporary copies.  */
-				size_t needed = hostlen + userlen + domainlen;
-
-				if (buflen - req->key_len - bufused < needed)
-				  {
-				    buflen += MAX (buflen, 2 * needed);
-				    /* Save offset in the old buffer.  We don't
-				       bother with the NULL check here since
-				       we'll do that later anyway.  */
-				    size_t nhostdiff = nhost - buffer;
-				    size_t nuserdiff = nuser - buffer;
-				    size_t ndomaindiff = ndomain - buffer;
-
-				    char *newbuf = xrealloc (buffer, buflen);
-				    /* Fix up the triplet pointers into the new
-				       buffer.  */
-				    nhost = (nhost ? newbuf + nhostdiff
-					     : NULL);
-				    nuser = (nuser ? newbuf + nuserdiff
-					     : NULL);
-				    ndomain = (ndomain ? newbuf + ndomaindiff
-					       : NULL);
-				    *tofreep = buffer = newbuf;
-				  }
-
-				nhost = memcpy (buffer + bufused,
-						nhost ?: "", hostlen);
-				nuser = memcpy ((char *) nhost + hostlen,
-						nuser ?: "", userlen);
-				ndomain = memcpy ((char *) nuser + userlen,
-						  ndomain ?: "", domainlen);
-			      }
-
-			    char *wp = buffer + buffilled;
-			    wp = memmove (wp, nhost ?: "", hostlen);
-			    wp += hostlen;
-			    wp = memmove (wp, nuser ?: "", userlen);
-			    wp += userlen;
-			    wp = memmove (wp, ndomain ?: "", domainlen);
-			    wp += domainlen;
-			    buffilled = wp - buffer;
+			    if (!(addgetnetgrentX_append (scratch, nhost)
+				  && addgetnetgrentX_append (scratch, nuser)
+				  && addgetnetgrentX_append (scratch, ndomain)))
+			      return send_notfound (fd);
 			    ++nentries;
 			  }
 			else
@@ -317,8 +330,8 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
 		      }
 		    else if (status == NSS_STATUS_TRYAGAIN && e == ERANGE)
 		      {
-			buflen *= 2;
-			*tofreep = buffer = xrealloc (buffer, buflen);
+			if (!scratch_buffer_grow (&scratch->tmp))
+			  return send_notfound (fd);
 		      }
 		    else if (status == NSS_STATUS_RETURN
 			     || status == NSS_STATUS_NOTFOUND
@@ -351,10 +364,17 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
       goto maybe_cache_add;
     }
 
-  total = buffilled;
+  /* Capture the result size without the key appended.   */
+  total = scratch->buffer_used;
+
+  /* Make a copy of the key.  The scratch buffer must not move after
+     this point.  */
+  key_copy = addgetnetgrentX_append_n (scratch, key, req->key_len);
+  if (key_copy == NULL)
+    return send_notfound (fd);
 
   /* Fill in the dataset.  */
-  dataset = (struct dataset *) buffer;
+  dataset = scratch->buffer.data;
   timeout = datahead_init_pos (&dataset->head, total + req->key_len,
 			       total - offsetof (struct dataset, resp),
 			       he == NULL ? 0 : dh->nreloads + 1,
@@ -363,11 +383,7 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
   dataset->resp.version = NSCD_VERSION;
   dataset->resp.found = 1;
   dataset->resp.nresults = nentries;
-  dataset->resp.result_len = buffilled - sizeof (*dataset);
-
-  assert (buflen - buffilled >= req->key_len);
-  key_copy = memcpy (buffer + buffilled, key, req->key_len);
-  buffilled += req->key_len;
+  dataset->resp.result_len = total - sizeof (*dataset);
 
   /* Now we can determine whether on refill we have to create a new
      record or not.  */
@@ -398,7 +414,7 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
     if (__glibc_likely (newp != NULL))
       {
 	/* Adjust pointer into the memory block.  */
-	key_copy = (char *) newp + (key_copy - buffer);
+	key_copy = (char *) newp + (key_copy - (char *) dataset);
 
 	dataset = memcpy (newp, dataset, total + req->key_len);
 	cacheable = true;
@@ -439,7 +455,7 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
     }
 
  out:
-  *resultp = dataset;
+  scratch->dataset = dataset;
 
   return timeout;
 }
@@ -460,6 +476,9 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req,
   if (user != NULL)
     key = strchr (key, '\0') + 1;
   const char *domain = *key++ ? key : NULL;
+  struct addgetnetgrentX_scratch scratch;
+
+  addgetnetgrentX_scratch_init (&scratch);
 
   if (__glibc_unlikely (debug_level > 0))
     {
@@ -475,12 +494,8 @@ 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;
-      tofree = NULL;
-    }
+    timeout = result->head.timeout;
   else
     {
       request_header req_get =
@@ -489,7 +504,10 @@ 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, &tofree);
+				 &scratch);
+      result = scratch.dataset;
+      if (timeout < 0)
+	goto out;
     }
 
   struct indataset
@@ -603,7 +621,7 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req,
     }
 
  out:
-  free (tofree);
+  addgetnetgrentX_scratch_free (&scratch);
   return timeout;
 }
 
@@ -613,11 +631,12 @@ 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);
+  struct addgetnetgrentX_scratch scratch;
+  addgetnetgrentX_scratch_init (&scratch);
+  time_t timeout = addgetnetgrentX (db, fd, req, key, uid, he, dh, &scratch);
+  addgetnetgrentX_scratch_free (&scratch);
+  if (timeout < 0)
+    timeout = 0;
   return timeout;
 }
 
@@ -661,5 +680,9 @@ readdinnetgr (struct database_dyn *db, struct hashentry *he,
       .key_len = he->len
     };
 
-  return addinnetgrX (db, -1, &req, db->data + he->key, he->owner, he, dh);
+  int timeout = addinnetgrX (db, -1, &req, db->data + he->key, he->owner,
+			     he, dh);
+  if (timeout < 0)
+    timeout = 0;
+  return timeout;
 }
