| From 099016b7e8d70a6d5dd814e788bba08d33d48426 Mon Sep 17 00:00:00 2001 |
| From: Tobias Stoeckmann <tobias@stoeckmann.org> |
| Date: Mon, 4 May 2020 19:41:16 +0200 |
| Subject: [PATCH 1/3] Protect array_list_del_idx against size_t overflow. |
| |
| If the assignment of stop overflows due to idx and count being |
| larger than SIZE_T_MAX in sum, out of boundary access could happen. |
| |
| It takes invalid usage of this function for this to happen, but |
| I decided to add this check so array_list_del_idx is as safe against |
| bad usage as the other arraylist functions. |
| --- |
| arraylist.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| diff --git a/arraylist.c b/arraylist.c |
| index 12ad8af6d3..e5524aca75 100644 |
| --- a/arraylist.c |
| +++ b/arraylist.c |
| @@ -136,6 +136,9 @@ int array_list_del_idx(struct array_list *arr, size_t idx, size_t count) |
| { |
| size_t i, stop; |
| |
| + /* Avoid overflow in calculation with large indices. */ |
| + if (idx > SIZE_T_MAX - count) |
| + return -1; |
| stop = idx + count; |
| if (idx >= arr->length || stop > arr->length) |
| return -1; |
| |
| From 77d935b7ae7871a1940cd827e850e6063044ec45 Mon Sep 17 00:00:00 2001 |
| From: Tobias Stoeckmann <tobias@stoeckmann.org> |
| Date: Mon, 4 May 2020 19:46:45 +0200 |
| Subject: [PATCH 2/3] Prevent division by zero in linkhash. |
| |
| If a linkhash with a size of zero is created, then modulo operations |
| are prone to division by zero operations. |
| |
| Purely protective measure against bad usage. |
| --- |
| linkhash.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| diff --git a/linkhash.c b/linkhash.c |
| index 7ea58c0abf..f05cc38030 100644 |
| --- a/linkhash.c |
| +++ b/linkhash.c |
| @@ -12,6 +12,7 @@ |
| |
| #include "config.h" |
| |
| +#include <assert.h> |
| #include <limits.h> |
| #include <stdarg.h> |
| #include <stddef.h> |
| @@ -499,6 +500,8 @@ struct lh_table *lh_table_new(int size, lh_entry_free_fn *free_fn, lh_hash_fn *h |
| int i; |
| struct lh_table *t; |
| |
| + /* Allocate space for elements to avoid divisions by zero. */ |
| + assert(size > 0); |
| t = (struct lh_table *)calloc(1, sizeof(struct lh_table)); |
| if (!t) |
| return NULL; |
| |
| From d07b91014986900a3a75f306d302e13e005e9d67 Mon Sep 17 00:00:00 2001 |
| From: Tobias Stoeckmann <tobias@stoeckmann.org> |
| Date: Mon, 4 May 2020 19:47:25 +0200 |
| Subject: [PATCH 3/3] Fix integer overflows. |
| |
| The data structures linkhash and printbuf are limited to 2 GB in size |
| due to a signed integer being used to track their current size. |
| |
| If too much data is added, then size variable can overflow, which is |
| an undefined behaviour in C programming language. |
| |
| Assuming that a signed int overflow just leads to a negative value, |
| like it happens on many sytems (Linux i686/amd64 with gcc), then |
| printbuf is vulnerable to an out of boundary write on 64 bit systems. |
| --- |
| linkhash.c | 7 +++++-- |
| printbuf.c | 19 ++++++++++++++++--- |
| 2 files changed, 21 insertions(+), 5 deletions(-) |
| |
| diff --git a/linkhash.c b/linkhash.c |
| index f05cc38030..51e90b13a2 100644 |
| --- a/linkhash.c |
| +++ b/linkhash.c |
| @@ -580,9 +580,12 @@ int lh_table_insert_w_hash(struct lh_table *t, const void *k, const void *v, con |
| { |
| unsigned long n; |
| |
| - if (t->count >= t->size * LH_LOAD_FACTOR) |
| - if (lh_table_resize(t, t->size * 2) != 0) |
| + if (t->count >= t->size * LH_LOAD_FACTOR) { |
| + /* Avoid signed integer overflow with large tables. */ |
| + int new_size = INT_MAX / 2 < t->size ? t->size * 2 : INT_MAX; |
| + if (t->size == INT_MAX || lh_table_resize(t, new_size) != 0) |
| return -1; |
| + } |
| |
| n = h % t->size; |
| |
| diff --git a/printbuf.c b/printbuf.c |
| index 976c12dde5..00822fac4f 100644 |
| --- a/printbuf.c |
| +++ b/printbuf.c |
| @@ -15,6 +15,7 @@ |
| |
| #include "config.h" |
| |
| +#include <limits.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| @@ -65,10 +66,16 @@ static int printbuf_extend(struct printbuf *p, int min_size) |
| |
| if (p->size >= min_size) |
| return 0; |
| - |
| - new_size = p->size * 2; |
| - if (new_size < min_size + 8) |
| + /* Prevent signed integer overflows with large buffers. */ |
| + if (min_size > INT_MAX - 8) |
| + return -1; |
| + if (p->size > INT_MAX / 2) |
| new_size = min_size + 8; |
| + else { |
| + new_size = p->size * 2; |
| + if (new_size < min_size + 8) |
| + new_size = min_size + 8; |
| + } |
| #ifdef PRINTBUF_DEBUG |
| MC_DEBUG("printbuf_memappend: realloc " |
| "bpos=%d min_size=%d old_size=%d new_size=%d\n", |
| @@ -83,6 +90,9 @@ static int printbuf_extend(struct printbuf *p, int min_size) |
| |
| int printbuf_memappend(struct printbuf *p, const char *buf, int size) |
| { |
| + /* Prevent signed integer overflows with large buffers. */ |
| + if (size > INT_MAX - p->bpos - 1) |
| + return -1; |
| if (p->size <= p->bpos + size + 1) |
| { |
| if (printbuf_extend(p, p->bpos + size + 1) < 0) |
| @@ -100,6 +110,9 @@ int printbuf_memset(struct printbuf *pb, int offset, int charvalue, int len) |
| |
| if (offset == -1) |
| offset = pb->bpos; |
| + /* Prevent signed integer overflows with large buffers. */ |
| + if (len > INT_MAX - offset) |
| + return -1; |
| size_needed = offset + len; |
| if (pb->size < size_needed) |
| { |