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Revision 447ac906e189535e77dcb1f4bbe3f1bc917d4c12 authored by Patrick Steinhardt on 01 December 2022, 14:45:31 UTC, committed by Junio C Hamano on 05 December 2022, 06:14:16 UTC 
attr: fix out-of-bounds read with unreasonable amount of patterns
 
The `struct attr_stack` tracks the stack of all patterns together with
their attributes. When parsing a gitattributes file that has more than
2^31 such patterns though we may trigger multiple out-of-bounds reads on
64 bit platforms. This is because while the `num_matches` variable is an
unsigned integer, we always use a signed integer to iterate over them.

I have not been able to reproduce this issue due to memory constraints
on my systems. But despite the out-of-bounds reads, the worst thing that
can seemingly happen is to call free(3P) with a garbage pointer when
calling `attr_stack_free()`.

Fix this bug by using unsigned integers to iterate over the array. While
this makes the iteration somewhat awkward when iterating in reverse, it
is at least better than knowingly running into an out-of-bounds read.
While at it, convert the call to `ALLOC_GROW` to use `ALLOC_GROW_BY`
instead.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 34ace8b
Raw File
oidset.c 
#include "cache.h"
#include "oidset.h"

void oidset_init(struct oidset *set, size_t initial_size)
{
	memset(&set->set, 0, sizeof(set->set));
	if (initial_size)
		kh_resize_oid_set(&set->set, initial_size);
}

int oidset_contains(const struct oidset *set, const struct object_id *oid)
{
	khiter_t pos = kh_get_oid_set(&set->set, *oid);
	return pos != kh_end(&set->set);
}

int oidset_insert(struct oidset *set, const struct object_id *oid)
{
	int added;
	kh_put_oid_set(&set->set, *oid, &added);
	return !added;
}

int oidset_remove(struct oidset *set, const struct object_id *oid)
{
	khiter_t pos = kh_get_oid_set(&set->set, *oid);
	if (pos == kh_end(&set->set))
		return 0;
	kh_del_oid_set(&set->set, pos);
	return 1;
}

void oidset_clear(struct oidset *set)
{
	kh_release_oid_set(&set->set);
	oidset_init(set, 0);
}

int oidset_size(struct oidset *set)
{
	return kh_size(&set->set);
}

void oidset_parse_file(struct oidset *set, const char *path)
{
	oidset_parse_file_carefully(set, path, NULL, NULL);
}

void oidset_parse_file_carefully(struct oidset *set, const char *path,
				 oidset_parse_tweak_fn fn, void *cbdata)
{
	FILE *fp;
	struct strbuf sb = STRBUF_INIT;
	struct object_id oid;

	fp = fopen(path, "r");
	if (!fp)
		die("could not open object name list: %s", path);
	while (!strbuf_getline(&sb, fp)) {
		const char *p;
		const char *name;

		/*
		 * Allow trailing comments, leading whitespace
		 * (including before commits), and empty or whitespace
		 * only lines.
		 */
		name = strchr(sb.buf, '#');
		if (name)
			strbuf_setlen(&sb, name - sb.buf);
		strbuf_trim(&sb);
		if (!sb.len)
			continue;

		if (parse_oid_hex(sb.buf, &oid, &p) || *p != '\0')
			die("invalid object name: %s", sb.buf);
		if (fn && fn(&oid, cbdata))
			continue;
		oidset_insert(set, &oid);
	}
	if (ferror(fp))
		die_errno("Could not read '%s'", path);
	fclose(fp);
	strbuf_release(&sb);
}
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