From: Hou Tao houtao1@huawei.com

mainline inclusion from mainline-v6.12-rc5 commit 8421d4c8762bd022cb491f2f0f7019ef51b4f0a7 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IB705A CVE: CVE-2024-53099

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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If a newly-added link type doesn't invoke BPF_LINK_TYPE(), accessing bpf_link_type_strs[link->type] may result in an out-of-bounds access.

To spot such missed invocations early in the future, checking the validity of link->type in bpf_link_show_fdinfo() and emitting a warning when such invocations are missed.

Signed-off-by: Hou Tao houtao1@huawei.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20241024013558.1135167-3-houtao@huaweicloud.com Conflicts: kernel/bpf/syscall.c [The conflicts were due to some minor issue.] Signed-off-by: Pu Lehui pulehui@huawei.com --- kernel/bpf/syscall.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ad6d3306aec0..b9846d8a8bde 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2430,15 +2430,20 @@ static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp) { const struct bpf_link *link = filp->private_data; const struct bpf_prog *prog = link->prog; + enum bpf_link_type type = link->type; char prog_tag[sizeof(prog->tag) * 2 + 1] = { };

bin2hex(prog_tag, prog->tag, sizeof(prog->tag)); + if (type < ARRAY_SIZE(bpf_link_type_strs) && bpf_link_type_strs[type]) { + seq_printf(m, "link_type:\t%s\n", bpf_link_type_strs[type]); + } else { + WARN_ONCE(1, "missing BPF_LINK_TYPE(...) for link type %u\n", type); + seq_printf(m, "link_type:\t<%u>\n", type); + } seq_printf(m, - "link_type:\t%s\n" "link_id:\t%u\n" "prog_tag:\t%s\n" "prog_id:\t%u\n", - bpf_link_type_strs[link->type], link->id, prog_tag, prog->aux->id);