From 41332d6e3a430adc91e0af115b4261b0d2f116ec Mon Sep 17 00:00:00 2001 From: Yuntao Wang Date: Thu, 3 Mar 2022 08:59:21 +0800 Subject: libbpf: Add a check to ensure that page_cnt is non-zero The page_cnt parameter is used to specify the number of memory pages allocated for each per-CPU buffer, it must be non-zero and a power of 2. Currently, the __perf_buffer__new() function attempts to validate that the page_cnt is a power of 2 but forgets checking for the case where page_cnt is zero, we can fix it by replacing 'page_cnt & (page_cnt - 1)' with 'page_cnt == 0 || (page_cnt & (page_cnt - 1))'. If so, we also don't need to add a check in perf_buffer__new_v0_6_0() to make sure that page_cnt is non-zero and the check for zero in perf_buffer__new_raw_v0_6_0() can also be removed. The code will be cleaner and more readable. Signed-off-by: Yuntao Wang Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220303005921.53436-1-ytcoode@gmail.com --- tools/lib/bpf/libbpf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tools/lib') diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index be6480e260c4..81bf01d67671 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10951,7 +10951,7 @@ struct perf_buffer *perf_buffer__new_raw_v0_6_0(int map_fd, size_t page_cnt, { struct perf_buffer_params p = {}; - if (page_cnt == 0 || !attr) + if (!attr) return libbpf_err_ptr(-EINVAL); if (!OPTS_VALID(opts, perf_buffer_raw_opts)) @@ -10992,7 +10992,7 @@ static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt, __u32 map_info_len; int err, i, j, n; - if (page_cnt & (page_cnt - 1)) { + if (page_cnt == 0 || (page_cnt & (page_cnt - 1))) { pr_warn("page count should be power of two, but is %zu\n", page_cnt); return ERR_PTR(-EINVAL); -- cgit v1.2.3-70-g09d2