bpf: Check for integer overflow when using roundup_pow_of_two()

On 32-bit architecture, roundup_pow_of_two() can return 0 when the argument
has upper most bit set due to resulting 1UL << 32. Add a check for this case.

Fixes: d5a3b1f69186 ("bpf: introduce BPF_MAP_TYPE_STACK_TRACE")
Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127063653.3576-1-minhquangbui99@gmail.com

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index aea96b6..bfafbf1 100644 (file)
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -115,6 +115,8 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
 
        /* hash table size must be power of 2 */
        n_buckets = roundup_pow_of_two(attr->max_entries);
+       if (!n_buckets)
+               return ERR_PTR(-E2BIG);
 
        cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);
        cost += n_buckets * (value_size + sizeof(struct stack_map_bucket));