| From 052c57f132f04a3cf4148f87561618da1a6908b4 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. |
| |
| [james.hilliard1@gmail.com: backport from upstream commit |
| 052c57f132f04a3cf4148f87561618da1a6908b4] |
| Signed-off-by: James Hilliard <james.hilliard1@gmail.com> |
| --- |
| src/journal/journald-native.c | 5 +++++ |
| src/shared/journal-importer.h | 3 +++ |
| 2 files changed, 8 insertions(+) |
| |
| diff --git a/src/journal/journald-native.c b/src/journal/journald-native.c |
| index e86178e..d0fee2a 100644 |
| --- a/src/journal/journald-native.c |
| +++ b/src/journal/journald-native.c |
| @@ -141,6 +141,11 @@ 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, |
| diff --git a/src/shared/journal-importer.h b/src/shared/journal-importer.h |
| index 53354b7..7914c0c 100644 |
| --- a/src/shared/journal-importer.h |
| +++ b/src/shared/journal-importer.h |
| @@ -21,6 +21,9 @@ |
| #endif |
| #define LINE_CHUNK 8*1024u |
| |
| +/* The maximum number of fields in an entry */ |
| +#define ENTRY_FIELD_COUNT_MAX 1024 |
| + |
| struct iovec_wrapper { |
| struct iovec *iovec; |
| size_t size_bytes; |
| -- |
| 2.7.4 |
| |
