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attr: fix integer overflow with more than INT_MAX macros 

Attributes have a field that tracks the position in the `all_attrs`
array they're stored inside. This field gets set via `hashmap_get_size`
when adding the attribute to the global map of attributes. But while the
field is of type `int`, the value returned by `hashmap_get_size` is an
`unsigned int`. It can thus happen that the value overflows, where we
would now dereference teh `all_attrs` array at an out-of-bounds value.

We do have a sanity check for this overflow via an assert that verifies
the index matches the new hashmap's size. But asserts are not a proper
mechanism to detect against any such overflows as they may not in fact
be compiled into production code.

Fix this by using an `unsigned int` to track the index and convert the
assert to a call `die()`.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Patrick Steinhardt 2022-12-01 15:45:36 +01:00 committed by Junio C Hamano
parent 447ac906e1
commit e1e12e97ac
1 changed files with 5 additions and 5 deletions
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10
attr.c
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@ -28,7 +28,7 @@ static const char git_attr__unknown[] = "(builtin)unknown";
#endif
struct git_attr {
int attr_nr; /* unique attribute number */
unsigned int attr_nr; /* unique attribute number */
char name[FLEX_ARRAY]; /* attribute name */
};
@ -226,8 +226,8 @@ static const struct git_attr *git_attr_internal(const char *name, size_t namelen
a->attr_nr = hashmap_get_size(&g_attr_hashmap.map);
attr_hashmap_add(&g_attr_hashmap, a->name, namelen, a);
assert(a->attr_nr ==
(hashmap_get_size(&g_attr_hashmap.map) - 1));
if (a->attr_nr != hashmap_get_size(&g_attr_hashmap.map) - 1)
die(_("unable to add additional attribute"));
}
hashmap_unlock(&g_attr_hashmap);
@ -1064,7 +1064,7 @@ static void determine_macros(struct all_attrs_item *all_attrs,
for (i = stack->num_matches; i > 0; i--) {
const struct match_attr *ma = stack->attrs[i - 1];
if (ma->is_macro) {
int n = ma->u.attr->attr_nr;
unsigned int n = ma->u.attr->attr_nr;
if (!all_attrs[n].macro) {
all_attrs[n].macro = ma;
}
@ -1116,7 +1116,7 @@ void git_check_attr(const struct index_state *istate,
collect_some_attrs(istate, path, check);
for (i = 0; i < check->nr; i++) {
size_t n = check->items[i].attr->attr_nr;
unsigned int n = check->items[i].attr->attr_nr;
const char *value = check->all_attrs[n].value;
if (value == ATTR__UNKNOWN)
value = ATTR__UNSET;