From 4448f64c549c28175dd9af4e8f9a2e0c62ef6d38 Mon Sep 17 00:00:00 2001 From: Martin Kelly Date: Mon, 25 Sep 2023 14:50:32 -0700 Subject: [PATCH] libbpf: Refactor cleanup in ring_buffer__add Refactor the cleanup code in ring_buffer__add to use a unified err_out label. This reduces code duplication, as well as plugging a potential leak if mmap_sz != (__u64)(size_t)mmap_sz (currently this would miss unmapping tmp because ringbuf_unmap_ring isn't called). Signed-off-by: Martin Kelly Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20230925215045.2375758-2-martin.kelly@crowdstrike.com --- tools/lib/bpf/ringbuf.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index 02199364db13..29b0d19d920f 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -121,7 +121,7 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, err = -errno; pr_warn("ringbuf: failed to mmap consumer page for map fd=%d: %d\n", map_fd, err); - return libbpf_err(err); + goto err_out; } r->consumer_pos = tmp; @@ -131,16 +131,16 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, */ mmap_sz = rb->page_size + 2 * (__u64)info.max_entries; if (mmap_sz != (__u64)(size_t)mmap_sz) { + err = -E2BIG; pr_warn("ringbuf: ring buffer size (%u) is too big\n", info.max_entries); - return libbpf_err(-E2BIG); + goto err_out; } tmp = mmap(NULL, (size_t)mmap_sz, PROT_READ, MAP_SHARED, map_fd, rb->page_size); if (tmp == MAP_FAILED) { err = -errno; - ringbuf_unmap_ring(rb, r); pr_warn("ringbuf: failed to mmap data pages for map fd=%d: %d\n", map_fd, err); - return libbpf_err(err); + goto err_out; } r->producer_pos = tmp; r->data = tmp + rb->page_size; @@ -152,14 +152,17 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, e->data.fd = rb->ring_cnt; if (epoll_ctl(rb->epoll_fd, EPOLL_CTL_ADD, map_fd, e) < 0) { err = -errno; - ringbuf_unmap_ring(rb, r); pr_warn("ringbuf: failed to epoll add map fd=%d: %d\n", map_fd, err); - return libbpf_err(err); + goto err_out; } rb->ring_cnt++; return 0; + +err_out: + ringbuf_unmap_ring(rb, r); + return libbpf_err(err); } void ring_buffer__free(struct ring_buffer *rb)