From: Alexei Starovoitov <ast@kernel.org>
Date: Wed, 30 Oct 2019 23:30:19 +0000 (-0700)
Subject: bpf: Fix bpf jit kallsym access
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=af91acbc62999d62e2ca1e80f660d20561ca55d3;p=linux.git

bpf: Fix bpf jit kallsym access

Jiri reported crash when JIT is on, but net.core.bpf_jit_kallsyms is off.
bpf_prog_kallsyms_find() was skipping addr->bpf_prog resolution
logic in oops and stack traces. That's incorrect.
It should only skip addr->name resolution for 'cat /proc/kallsyms'.
That's what bpf_jit_kallsyms and bpf_jit_harden protect.

Fixes: 3dec541b2e63 ("bpf: Add support for BTF pointers to x86 JIT")
Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191030233019.1187404-1-ast@kernel.org
---

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 673f5d40a93e3..8d3fbc86ca5e2 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -668,9 +668,6 @@ static struct bpf_prog *bpf_prog_kallsyms_find(unsigned long addr)
 {
 	struct latch_tree_node *n;
 
-	if (!bpf_jit_kallsyms_enabled())
-		return NULL;
-
 	n = latch_tree_find((void *)addr, &bpf_tree, &bpf_tree_ops);
 	return n ?
 	       container_of(n, struct bpf_prog_aux, ksym_tnode)->prog :