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libbpf: Improve handling of corrupted ELF during map initialization

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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: bf82927125 ("libbpf: refactor map initialization")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191107020855.3834758-6-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2019-11-06 18:08:55 -08:00 committed by Daniel Borkmann
parent 994021a7e0
commit 98e527af30
1 changed files with 2 additions and 2 deletions
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4
tools/lib/bpf/libbpf.c
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@ -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++) {