[PATCH 4.9 24/49] bpf: Check for integer overflow when using roundup_pow_of_two()

[Greg Kroah-Hartman]

From: Bui Quang Minh <minhquangbui99@xxxxxxxxx>

[ Upstream commit 6183f4d3a0a2ad230511987c6c362ca43ec0055f ]

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@xxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210127063653.3576-1-minhquangbui99@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 kernel/bpf/stackmap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index a2a232dec2363..2fdf6f96f9762 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -70,6 +70,8 @@ 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);
 	if (cost >= U32_MAX - PAGE_SIZE)
-- 
2.27.0