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83 lines
2.5 KiB
83 lines
2.5 KiB
From d07b91014986900a3a75f306d302e13e005e9d67 Mon Sep 17 00:00:00 2001
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From: Tobias Stoeckmann <tobias@stoeckmann.org>
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Date: Mon, 4 May 2020 19:47:25 +0200
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Subject: [PATCH] Fix integer overflows.
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The data structures linkhash and printbuf are limited to 2 GB in size
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due to a signed integer being used to track their current size.
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If too much data is added, then size variable can overflow, which is
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an undefined behaviour in C programming language.
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Assuming that a signed int overflow just leads to a negative value,
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like it happens on many sytems (Linux i686/amd64 with gcc), then
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printbuf is vulnerable to an out of boundary write on 64 bit systems.
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---
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linkhash.c | 7 +++++--
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printbuf.c | 19 ++++++++++++++++---
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2 files changed, 21 insertions(+), 5 deletions(-)
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--- a/linkhash.c
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+++ b/linkhash.c
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@@ -498,7 +498,12 @@ int lh_table_insert(struct lh_table *t,
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unsigned long h, n;
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t->inserts++;
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- if(t->count >= t->size * LH_LOAD_FACTOR) lh_table_resize(t, t->size * 2);
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+ if(t->count >= t->size * LH_LOAD_FACTOR) {
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+ /* Avoid signed integer overflow with large tables. */
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+ int new_size = (t->size > INT_MAX / 2) ? INT_MAX : (t->size * 2);
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+ if (t->size != INT_MAX)
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+ lh_table_resize(t, new_size);
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+ }
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h = t->hash_fn(k);
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n = h % t->size;
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--- a/printbuf.c
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+++ b/printbuf.c
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@@ -15,6 +15,7 @@
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#include "config.h"
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+#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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@@ -63,7 +64,16 @@ static int printbuf_extend(struct printb
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if (p->size >= min_size)
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return 0;
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- new_size = json_max(p->size * 2, min_size + 8);
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+ /* Prevent signed integer overflows with large buffers. */
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+ if (min_size > INT_MAX - 8)
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+ return -1;
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+ if (p->size > INT_MAX / 2)
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+ new_size = min_size + 8;
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+ else {
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+ new_size = p->size * 2;
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+ if (new_size < min_size + 8)
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+ new_size = min_size + 8;
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+ }
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#ifdef PRINTBUF_DEBUG
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MC_DEBUG("printbuf_memappend: realloc "
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"bpos=%d min_size=%d old_size=%d new_size=%d\n",
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@@ -78,6 +88,9 @@ static int printbuf_extend(struct printb
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int printbuf_memappend(struct printbuf *p, const char *buf, int size)
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{
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+ /* Prevent signed integer overflows with large buffers. */
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+ if (size > INT_MAX - p->bpos - 1)
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+ return -1;
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if (p->size <= p->bpos + size + 1) {
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if (printbuf_extend(p, p->bpos + size + 1) < 0)
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return -1;
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@@ -94,6 +107,9 @@ int printbuf_memset(struct printbuf *pb,
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if (offset == -1)
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offset = pb->bpos;
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+ /* Prevent signed integer overflows with large buffers. */
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+ if (len > INT_MAX - offset)
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+ return -1;
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size_needed = offset + len;
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if (pb->size < size_needed)
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{
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