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bpf: fix arraymap NULL deref and missing overflow and zero size checks

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- fix NULL pointer dereference:
kernel/bpf/arraymap.c:41 array_map_alloc() error: potential null dereference 'array'.  (kzalloc returns null)
kernel/bpf/arraymap.c:41 array_map_alloc() error: we previously assumed 'array' could be null (see line 40)

- integer overflow check was missing in arraymap
(hashmap checks for overflow via kmalloc_array())

- arraymap can round_up(value_size, 8) to zero. check was missing.

- hashmap was missing zero size check as well, since roundup_pow_of_two() can
truncate into zero

- found a typo in the arraymap comment and unnecessary empty line

Fix all of these issues and make both overflow checks explicit U32 in size.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2014-11-18 17:32:16 -08:00 committed by David S. Miller
parent fcd4d35ecc
commit daaf427c6a
2 changed files with 16 additions and 6 deletions
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17
kernel/bpf/arraymap.c
View File

@ -25,7 +25,7 @@ struct bpf_array {
static struct bpf_map *array_map_alloc(union bpf_attr *attr)
{
struct bpf_array *array;
u32 elem_size;
u32 elem_size, array_size;
/* check sanity of attributes */
if (attr->max_entries == 0 || attr->key_size != 4 ||
@ -34,11 +34,17 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
elem_size = round_up(attr->value_size, 8);
/* check round_up into zero and u32 overflow */
if (elem_size == 0 ||
attr->max_entries > (U32_MAX - sizeof(*array)) / elem_size)
return ERR_PTR(-ENOMEM);
array_size = sizeof(*array) + attr->max_entries * elem_size;
/* allocate all map elements and zero-initialize them */
array = kzalloc(sizeof(*array) + attr->max_entries * elem_size,
GFP_USER | __GFP_NOWARN);
array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
if (!array) {
array = vzalloc(array->map.max_entries * array->elem_size);
array = vzalloc(array_size);
if (!array)
return ERR_PTR(-ENOMEM);
}
@ -51,7 +57,6 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
array->elem_size = elem_size;
return &array->map;
}
/* Called from syscall or from eBPF program */
@ -101,7 +106,7 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
return -E2BIG;
if (map_flags == BPF_NOEXIST)
/* all elemenets already exist */
/* all elements already exist */
return -EEXIST;
memcpy(array->value + array->elem_size * index, value, array->elem_size);

5
kernel/bpf/hashtab.c
View File

@ -65,6 +65,11 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
goto free_htab;
err = -ENOMEM;
/* prevent zero size kmalloc and check for u32 overflow */
if (htab->n_buckets == 0 ||
htab->n_buckets > U32_MAX / sizeof(struct hlist_head))
goto free_htab;
htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct hlist_head),
GFP_USER | __GFP_NOWARN);