From: Shung-Hsi Yu shung-hsi.yu@suse.com

maillist inclusion category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5WLXN CVE: CVE-2022-3606

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/t...

--------------------------------

When there are no program sections, obj->programs is left unallocated, and find_prog_by_sec_insn()'s search lands on &obj->programs[0] == NULL, and will cause null-pointer dereference in the following access to prog->sec_idx.

Guard the search with obj->nr_programs similar to what's being done in __bpf_program__iter() to prevent null-pointer access from happening.

Fixes: db2b8b06423c ("libbpf: Support CO-RE relocations for multi-prog sections") Signed-off-by: Shung-Hsi Yu shung-hsi.yu@suse.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20221012022353.7350-4-shung-hsi.yu@suse.com Signed-off-by: Pu Lehui pulehui@huawei.com Reviewed-by: Kuohai Xu xukuohai@huawei.com Reviewed-by: Xiu Jianfeng xiujianfeng@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- tools/lib/bpf/libbpf.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 314fb1202d08..2b997a981052 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -3479,6 +3479,9 @@ static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj, int l = 0, r = obj->nr_programs - 1, m; struct bpf_program *prog;

+ if (!obj->nr_programs) + return NULL; + while (l < r) { m = l + (r - l + 1) / 2; prog = &obj->programs[m];