From 9f53d3cded6cf7eccb40c810dfb8fd6e101c7a3b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
Date: Wed, 5 Dec 2018 22:45:02 +0100
Subject: [PATCH] journald: set a limit on the number of fields (1k)
We allocate a iovec entry for each field, so with many short entries,
our memory usage and processing time can be large, even with a relatively
small message size. Let's refuse overly long entries.
CVE-2018-16865
https://bugzilla.redhat.com/show_bug.cgi?id=1653861
What from I can see, the problem is not from an alloca, despite what the CVE
description says, but from the attack multiplication that comes from creating
many very small iovecs: (void* + size_t) for each three bytes of input message.
(cherry-picked from commit 052c57f132f04a3cf4148f87561618da1a6908b4)
Resolves: #1664977
---
src/journal/journal-file.h | 3 +++
src/journal/journald-native.c | 5 +++++
2 files changed, 8 insertions(+)
diff --git a/src/journal/journal-file.h b/src/journal/journal-file.h
index c8114ee2d0..cd8a48a364 100644
--- a/src/journal/journal-file.h
+++ b/src/journal/journal-file.h
@@ -165,6 +165,9 @@ int journal_file_open_reliably(
* files without adding too many zeros. */
#define OFSfmt "%06"PRIx64
+/* The maximum number of fields in an entry */
+#define ENTRY_FIELD_COUNT_MAX 1024
+
static inline bool VALID_REALTIME(uint64_t u) {
/* This considers timestamps until the year 3112 valid. That should be plenty room... */
return u > 0 && u < (1ULL << 55);
diff --git a/src/journal/journald-native.c b/src/journal/journald-native.c
index 5ff22a10af..951d092053 100644
--- a/src/journal/journald-native.c
+++ b/src/journal/journald-native.c
@@ -140,6 +140,11 @@ static int server_process_entry(
}
/* A property follows */
+ if (n > ENTRY_FIELD_COUNT_MAX) {
+ log_debug("Received an entry that has more than " STRINGIFY(ENTRY_FIELD_COUNT_MAX) " fields, ignoring entry.");
+ r = 1;
+ goto finish;
+ }
/* n existing properties, 1 new, +1 for _TRANSPORT */
if (!GREEDY_REALLOC(iovec, m,