linux-kernel - [PATCH 5.2 22/94] libbpf: set BTF FD for prog only when there is supported .BTF.ext data

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sun,  8 Sep 2019 13:41:18 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andrey Ignatov <rdna@...com>,
        Andrii Nakryiko <andriin@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.2 22/94] libbpf: set BTF FD for prog only when there is supported .BTF.ext data

[ Upstream commit 3415ec643e7bd644b03026efbe2f2b36cbe9b34b ]

5d01ab7bac46 ("libbpf: fix erroneous multi-closing of BTF FD")
introduced backwards-compatibility issue, manifesting itself as -E2BIG
error returned on program load due to unknown non-zero btf_fd attribute
value for BPF_PROG_LOAD sys_bpf() sub-command.

This patch fixes bug by ensuring that we only ever associate BTF FD with
program if there is a BTF.ext data that was successfully loaded into
kernel, which automatically means kernel supports func_info/line_info
and associated BTF FD for progs (checked and ensured also by BTF
sanitization code).

Fixes: 5d01ab7bac46 ("libbpf: fix erroneous multi-closing of BTF FD")
Reported-by: Andrey Ignatov <rdna@...com>
Signed-off-by: Andrii Nakryiko <andriin@...com>
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/lib/bpf/libbpf.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 21355f6be2434..0ccf6aa533ae9 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2071,7 +2071,11 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	load_attr.license = license;
 	load_attr.kern_version = kern_version;
 	load_attr.prog_ifindex = prog->prog_ifindex;
-	btf_fd = bpf_object__btf_fd(prog->obj);
+	/* if .BTF.ext was loaded, kernel supports associated BTF for prog */
+	if (prog->obj->btf_ext)
+		btf_fd = bpf_object__btf_fd(prog->obj);
+	else
+		btf_fd = -1;
 	load_attr.prog_btf_fd = btf_fd >= 0 ? btf_fd : 0;
 	load_attr.func_info = prog->func_info;
 	load_attr.func_info_rec_size = prog->func_info_rec_size;
-- 
2.20.1