From 0f15f88443e52a0f69e579f7590bbebde92bc850 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 6 Nov 2019 18:08:55 -0800 Subject: [PATCH] libbpf: Improve handling of corrupted ELF during map initialization If we get ELF file with "maps" section, but no symbols pointing to it, we'll end up with division by zero. Add check against this situation and exit early with error. Found by Coverity scan against Github libbpf sources. Fixes: bf82927125dd ("libbpf: refactor map initialization") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20191107020855.3834758-6-andriin@fb.com --- src/libbpf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/libbpf.c b/src/libbpf.c index 3ef73a2..fde6cb3 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -956,13 +956,13 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict) pr_debug("maps in %s: %d maps in %zd bytes\n", obj->path, nr_maps, data->d_size); - map_def_sz = data->d_size / nr_maps; - if (!data->d_size || (data->d_size % nr_maps) != 0) { + if (!data->d_size || nr_maps == 0 || (data->d_size % nr_maps) != 0) { pr_warn("unable to determine map definition size " "section %s, %d maps in %zd bytes\n", obj->path, nr_maps, data->d_size); return -EINVAL; } + map_def_sz = data->d_size / nr_maps; /* Fill obj->maps using data in "maps" section. */ for (i = 0; i < nr_syms; i++) {