Re: [syzbot] [bpf?] KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok

[Kohei Enju]

> syzbot found the following issue on:
> 
> HEAD commit:    f28214603dc6 Merge branch 'selftests-bpf-move-test_lwt_seg..
> git tree:       bpf-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=15f84664580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=b7bde34acd8f53b1
> dashboard link: https://syzkaller.appspot.com/bug?extid=a5964227adc0f904549c
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16450ba8580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11f5fa54580000

#syz test

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7788,6 +7788,12 @@ static int check_atomic_rmw(struct bpf_verifier_env *env,
 static int check_atomic_load(struct bpf_verifier_env *env,
 			     struct bpf_insn *insn)
 {
+	int err;
+
+	err = check_reg_arg(env, insn->src_reg, SRC_OP);
+	if (err)
+		return err;
+
 	if (!atomic_ptr_type_ok(env, insn->src_reg, insn)) {
 		verbose(env, "BPF_ATOMIC loads from R%d %s is not allowed\n",
 			insn->src_reg,
@@ -7801,6 +7807,12 @@ static int check_atomic_load(struct bpf_verifier_env *env,
 static int check_atomic_store(struct bpf_verifier_env *env,
 			      struct bpf_insn *insn)
 {
+	int err;
+
+	err = check_reg_arg(env, insn->dst_reg, SRC_OP);
+	if (err)
+		return err;
+
 	if (!atomic_ptr_type_ok(env, insn->dst_reg, insn)) {
 		verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n",
 			insn->dst_reg,