From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
Date: Tue, 10 Dec 2019 19:14:12 +0100
Subject: bpftool: Don't crash on missing jited insns or ksyms
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Patch-mainline: v5.5-rc3
Git-commit: 5b79bcdf03628a3a9ee04d9cd5fabcf61a8e20be
References: bsc#1155518

When the kptr_restrict sysctl is set, the kernel can fail to return
jited_ksyms or jited_prog_insns, but still have positive values in
nr_jited_ksyms and jited_prog_len. This causes bpftool to crash when
trying to dump the program because it only checks the len fields not
the actual pointers to the instructions and ksyms.

Fix this by adding the missing checks.

Fixes: 71bb428fe2c1 ("tools: bpf: add bpftool")
Fixes: f84192ee00b7 ("tools: bpftool: resolve calls without using imm field")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191210181412.151226-1-toke@redhat.com
Acked-by: Gary Lin <glin@suse.com>
---
 tools/bpf/bpftool/prog.c          |    2 +-
 tools/bpf/bpftool/xlated_dumper.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -493,7 +493,7 @@ static int do_dump(int argc, char **argv
 
 	info = &info_linear->info;
 	if (mode == DUMP_JITED) {
-		if (info->jited_prog_len == 0) {
+		if (info->jited_prog_len == 0 || !info->jited_prog_insns) {
 			p_info("no instructions returned");
 			goto err_free;
 		}
--- a/tools/bpf/bpftool/xlated_dumper.c
+++ b/tools/bpf/bpftool/xlated_dumper.c
@@ -174,7 +174,7 @@ static const char *print_call(void *priv
 	struct kernel_sym *sym;
 
 	if (insn->src_reg == BPF_PSEUDO_CALL &&
-	    (__u32) insn->imm < dd->nr_jited_ksyms)
+	    (__u32) insn->imm < dd->nr_jited_ksyms && dd->jited_ksyms)
 		address = dd->jited_ksyms[insn->imm];
 
 	sym = kernel_syms_search(dd, address);