linux-kernel - [PATCH AUTOSEL 5.5 133/542] bpftool: Don't crash on missing xlated program instructions

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Message-Id: <20200214154854.6746-133-sashal@kernel.org>
Date:   Fri, 14 Feb 2020 10:42:05 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Toke Høiland-Jørgensen <toke@...hat.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Quentin Monnet <quentin@...valent.com>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 5.5 133/542] bpftool: Don't crash on missing xlated program instructions

From: Toke Høiland-Jørgensen <toke@...hat.com>

[ Upstream commit d95f1e8b462c4372ac409886070bb8719d8a4d3a ]

Turns out the xlated program instructions can also be missing if
kptr_restrict sysctl is set. This means that the previous fix to check the
jited_prog_insns pointer was insufficient; add another check of the
xlated_prog_insns pointer as well.

Fixes: 5b79bcdf0362 ("bpftool: Don't crash on missing jited insns or ksyms")
Fixes: cae73f233923 ("bpftool: use bpf_program__get_prog_info_linear() in prog.c:do_dump()")
Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Reviewed-by: Quentin Monnet <quentin@...valent.com>
Link: https://lore.kernel.org/bpf/20200206102906.112551-1-toke@redhat.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/bpf/bpftool/prog.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 2ce9c5ba19347..9288be1d6bf0e 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -500,7 +500,7 @@ static int do_dump(int argc, char **argv)
 		buf = (unsigned char *)(info->jited_prog_insns);
 		member_len = info->jited_prog_len;
 	} else {	/* DUMP_XLATED */
-		if (info->xlated_prog_len == 0) {
+		if (info->xlated_prog_len == 0 || !info->xlated_prog_insns) {
 			p_err("error retrieving insn dump: kernel.kptr_restrict set?");
 			goto err_free;
 		}
-- 
2.20.1