This is a note to let you know that I've just added the patch titled
bpf: Check validity of link->type in bpf_link_show_fdinfo()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-check-validity-of-link-type-in-bpf_link_show_fdi.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ee9f0443b129c3f50d6b792e5160fe4e2647da2a
Author: Hou Tao <houtao1@xxxxxxxxxx>
Date: Fri Dec 27 14:04:35 2024 +0800
bpf: Check validity of link->type in bpf_link_show_fdinfo()
commit 8421d4c8762bd022cb491f2f0f7019ef51b4f0a7 upstream.
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@xxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20241024013558.1135167-3-houtao@xxxxxxxxxxxxxxx
[ shung-hsi.yu: break up existing seq_printf() call since commit 68b04864ca42
("bpf: Create links for BPF struct_ops maps.") is not present ]
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index d4b4a47081b5..37aa1e319165 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2522,16 +2522,21 @@ 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] = { };
+ 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_id:\t%u\n", link->id);
+
bin2hex(prog_tag, prog->tag, sizeof(prog->tag));
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);
if (link->ops->show_fdinfo)
