Commit 5b79bcdf authored Dec 10, 2019 by Toke Høiland-Jørgensen Committed by Daniel Borkmann Dec 11, 2019

bpftool: Don't crash on missing jited insns or ksyms



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: 71bb428f ("tools: bpf: add bpftool")
Fixes: f84192ee ("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

parent 4c80c7bc

tools/bpf/bpftool/prog.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;
		}

tools/bpf/bpftool/xlated_dumper.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -174,7 +174,7 @@ static const char print_call(void private_data,
		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);

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