libbpf: Fix potential multiplication overflow in mmap() size calculation

Prevent potential overflow performed in 32-bit integers, before assigning
result to size_t. Reported by LGTM static analysis.

Fixes: ac9baa3fdfc8 ("libbpf: Refactor global data map initialization")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200117060801.1311525-4-andriin@fb.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3b0b88c3377d22ddfac00a488d9e9aa20999ebce..fc41c3f2e983b6bc235393ecb2d3c4a365f11122 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1283,7 +1283,7 @@ static size_t bpf_map_mmap_sz(const struct bpf_map *map)
        long page_sz = sysconf(_SC_PAGE_SIZE);
        size_t map_sz;
 
-       map_sz = roundup(map->def.value_size, 8) * map->def.max_entries;
+       map_sz = (size_t)roundup(map->def.value_size, 8) * map->def.max_entries;
        map_sz = roundup(map_sz, page_sz);
        return map_sz;
 }