From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>
Subject: [PATCH v2 bpf-next 2/3] libbpf: fix crash if SEC("freplace") programs don't have attach_prog_fd set
Date: Fri, 9 Sep 2022 12:30:52 -0700 [thread overview]
Message-ID: <20220909193053.577111-3-andrii@kernel.org> (raw)
In-Reply-To: <20220909193053.577111-1-andrii@kernel.org>
Fix SIGSEGV caused by libbpf trying to find attach type in vmlinux BTF
for freplace programs. It's wrong to search in vmlinux BTF and libbpf
doesn't even mark vmlinux BTF as required for freplace programs. So
trying to search anything in obj->vmlinux_btf might cause NULL
dereference if nothing else in BPF object requires vmlinux BTF.
Instead, error out if freplace (EXT) program doesn't specify
attach_prog_fd during at the load time.
Fixes: 91abb4a6d79d ("libbpf: Support attachment of BPF tracing programs to kernel modules")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/lib/bpf/libbpf.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3ad139285fad..2ca30ccc774c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9084,11 +9084,15 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attac
int err = 0;
/* BPF program's BTF ID */
- if (attach_prog_fd) {
+ if (prog->type == BPF_PROG_TYPE_EXT || attach_prog_fd) {
+ if (!attach_prog_fd) {
+ pr_warn("prog '%s': attach program FD is not set\n", prog->name);
+ return -EINVAL;
+ }
err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd);
if (err < 0) {
- pr_warn("failed to find BPF program (FD %d) BTF ID for '%s': %d\n",
- attach_prog_fd, attach_name, err);
+ pr_warn("prog '%s': failed to find BPF program (FD %d) BTF ID for '%s': %d\n",
+ prog->name, attach_prog_fd, attach_name, err);
return err;
}
*btf_obj_fd = 0;
@@ -9105,7 +9109,8 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attac
err = find_kernel_btf_id(prog->obj, attach_name, attach_type, btf_obj_fd, btf_type_id);
}
if (err) {
- pr_warn("failed to find kernel BTF type ID of '%s': %d\n", attach_name, err);
+ pr_warn("prog '%s': failed to find kernel BTF type ID of '%s': %d\n",
+ prog->name, attach_name, err);
return err;
}
return 0;
--
2.30.2
next prev parent reply other threads:[~2022-09-09 19:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-09 19:30 [PATCH v2 bpf-next 0/3] BPF mass-verification veristat tool Andrii Nakryiko
2022-09-09 19:30 ` [PATCH v2 bpf-next 1/3] selftests/bpf: fix test_verif_scale{1,3} SEC() annotations Andrii Nakryiko
2022-09-09 19:30 ` Andrii Nakryiko [this message]
2022-09-09 19:30 ` [PATCH v2 bpf-next 3/3] selftests/bpf: add veristat tool for mass-verifying BPF object files Andrii Nakryiko
2022-09-16 20:50 ` Daniel Borkmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220909193053.577111-3-andrii@kernel.org \
--to=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kernel-team@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).