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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
oidmap.c 
#include "cache.h"
#include "oidmap.h"

static int oidmap_neq(const void *hashmap_cmp_fn_data,
		      const struct hashmap_entry *e1,
		      const struct hashmap_entry *e2,
		      const void *keydata)
{
	const struct oidmap_entry *a, *b;

	a = container_of(e1, const struct oidmap_entry, internal_entry);
	b = container_of(e2, const struct oidmap_entry, internal_entry);

	if (keydata)
		return !oideq(&a->oid, (const struct object_id *) keydata);
	return !oideq(&a->oid, &b->oid);
}

void oidmap_init(struct oidmap *map, size_t initial_size)
{
	hashmap_init(&map->map, oidmap_neq, NULL, initial_size);
}

void oidmap_free(struct oidmap *map, int free_entries)
{
	if (!map)
		return;

	/* TODO: make oidmap itself not depend on struct layouts */
	hashmap_clear_(&map->map, free_entries ? 0 : -1);
}

void *oidmap_get(const struct oidmap *map, const struct object_id *key)
{
	if (!map->map.cmpfn)
		return NULL;

	return hashmap_get_from_hash(&map->map, oidhash(key), key);
}

void *oidmap_remove(struct oidmap *map, const struct object_id *key)
{
	struct hashmap_entry entry;

	if (!map->map.cmpfn)
		oidmap_init(map, 0);

	hashmap_entry_init(&entry, oidhash(key));
	return hashmap_remove(&map->map, &entry, key);
}

void *oidmap_put(struct oidmap *map, void *entry)
{
	struct oidmap_entry *to_put = entry;

	if (!map->map.cmpfn)
		oidmap_init(map, 0);

	hashmap_entry_init(&to_put->internal_entry, oidhash(&to_put->oid));
	return hashmap_put(&map->map, &to_put->internal_entry);
}
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