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

Kohei Enju posted 1 patch 9 months, 1 week ago
[syzbot] [bpf?] KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok
Posted by Kohei Enju 9 months, 1 week ago
> syzbot tried to test the proposed patch but the build/boot failed:
> 
> failed to apply patch:
> checking file kernel/bpf/verifier.c
> patch: **** unexpected end of file in patch

Oh, something wrong with format, such as trailing space...?

#syz test

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 3303a3605ee8..0120cc325078 100644
--- 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_load_mem(env, insn, true, false, false, "atomic_load");
+	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,
@@ -7795,12 +7801,18 @@ static int check_atomic_load(struct bpf_verifier_env *env,
 		return -EACCES;
 	}
 
-	return check_load_mem(env, insn, true, false, false, "atomic_load");
+	return 0;
 }
 
 static int check_atomic_store(struct bpf_verifier_env *env,
 			      struct bpf_insn *insn)
 {
+	int err;
+
+	err = check_store_reg(env, insn, true);
+	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,
@@ -7808,7 +7820,7 @@ static int check_atomic_store(struct bpf_verifier_env *env,
 		return -EACCES;
 	}
 
-	return check_store_reg(env, insn, true);
+	return 0;
 }
 
 static int check_atomic(struct bpf_verifier_env *env, struct bpf_insn *insn)
-- 
2.48.1
Re: [syzbot] [bpf?] KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok
Posted by syzbot 9 months, 1 week ago
Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+a5964227adc0f904549c@syzkaller.appspotmail.com
Tested-by: syzbot+a5964227adc0f904549c@syzkaller.appspotmail.com

Tested on:

commit:         2d7597d6 selftests/bpf: Fix sockopt selftest failure o..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1397704c580000
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
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1188ae54580000

Note: testing is done by a robot and is best-effort only.