linux-kernel - Re: [syzbot] [bpf?] UBSAN: array-index-out-of-bounds in check_stack_range

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Date: Fri, 22 Mar 2024 08:11:05 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+33f4297b5f927648741a@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bpf?] UBSAN: array-index-out-of-bounds in check_stack_range_initialized

please test oob in check_stack_range_initialized

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1dd3b99d1bb9..80b9ae2b90bb 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7177,6 +7177,11 @@ static int check_stack_range_initialized(
 		return 0;
 	}
 
+	if (INT_MIN - access_size > max_off) {
+		verbose(env, "invalid access size\n");
+		return -EACCES;
+	}
+
 	for (i = min_off; i < max_off + access_size; i++) {
 		u8 *stype;
 
@@ -8589,6 +8594,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		return 0;
 	}
 
+	printk("1meta:%p, maptr:%p, ks:%d, kv:%d,%s\n",
+		meta, meta->map_ptr, meta->map_ptr->key_size, meta->map_ptr->value_size, __func__);
 	if (type_is_pkt_pointer(type) &&
 	    !may_access_direct_pkt_data(env, meta, BPF_READ)) {
 		verbose(env, "helper access to the packet is not allowed\n");
@@ -8704,6 +8711,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 			verbose(env, "invalid map_ptr to access map->key\n");
 			return -EACCES;
 		}
+		printk("meta:%p, maptr:%p, ks:%d, reg->map_ptr:%p, %s\n",
+			meta, meta->map_ptr, meta->map_ptr->key_size, reg->map_ptr, __func__);
 		err = check_helper_mem_access(env, regno,
 					      meta->map_ptr->key_size, false,
 					      NULL);
@@ -8721,6 +8730,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 			return -EACCES;
 		}
 		meta->raw_mode = arg_type & MEM_UNINIT;
+		printk("meta:%p, maptr:%p, vs:%d, reg->map_ptr:%p, %s\n",
+			meta, meta->map_ptr, meta->map_ptr->value_size, reg->map_ptr, __func__);
 		err = check_helper_mem_access(env, regno,
 					      meta->map_ptr->value_size, false,
 					      meta);
@@ -10248,6 +10259,8 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
 
 	meta.func_id = func_id;
 	/* check args */
+	printk("meta:%p, maptr:%p, %s\n",
+		&meta, meta.map_ptr, __func__);
 	for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
 		err = check_func_arg(env, i, &meta, fn, insn_idx);
 		if (err)