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bpf: fix arraymap NULL deref and missing overflow and zero size checks
- 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>
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@ -25,7 +25,7 @@ struct bpf_array {
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static struct bpf_map *array_map_alloc(union bpf_attr *attr)
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{
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struct bpf_array *array;
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u32 elem_size;
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u32 elem_size, array_size;
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/* check sanity of attributes */
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if (attr->max_entries == 0 || attr->key_size != 4 ||
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@ -34,11 +34,17 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
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elem_size = round_up(attr->value_size, 8);
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/* check round_up into zero and u32 overflow */
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if (elem_size == 0 ||
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attr->max_entries > (U32_MAX - sizeof(*array)) / elem_size)
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return ERR_PTR(-ENOMEM);
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array_size = sizeof(*array) + attr->max_entries * elem_size;
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/* allocate all map elements and zero-initialize them */
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array = kzalloc(sizeof(*array) + attr->max_entries * elem_size,
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GFP_USER | __GFP_NOWARN);
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array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
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if (!array) {
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array = vzalloc(array->map.max_entries * array->elem_size);
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array = vzalloc(array_size);
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if (!array)
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return ERR_PTR(-ENOMEM);
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}
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@ -51,7 +57,6 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
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array->elem_size = elem_size;
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return &array->map;
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}
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/* Called from syscall or from eBPF program */
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@ -101,7 +106,7 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
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return -E2BIG;
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if (map_flags == BPF_NOEXIST)
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/* all elemenets already exist */
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/* all elements already exist */
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return -EEXIST;
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memcpy(array->value + array->elem_size * index, value, array->elem_size);
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@ -65,6 +65,11 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
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goto free_htab;
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err = -ENOMEM;
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/* prevent zero size kmalloc and check for u32 overflow */
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if (htab->n_buckets == 0 ||
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htab->n_buckets > U32_MAX / sizeof(struct hlist_head))
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goto free_htab;
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htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct hlist_head),
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GFP_USER | __GFP_NOWARN);
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