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Fix integer overflows.

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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.
This commit is contained in:
Tobias Stoeckmann
2020-05-04 19:47:25 +02:00
parent 77d935b7ae
commit d07b910149
2 changed files with 21 additions and 5 deletions
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7
linkhash.c
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@@ -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;