commit 5c6f25887963f15492b604dd25cb149c501bbabf
author Greg Kroah-Hartman <gregkh@linuxfoundation.org> Fri Mar 20 17:22:58 2020 +0100
committer Daniel Borkmann <daniel@iogearbox.net> Fri Mar 20 21:05:22 2020 +0100
tree 0ca35ad39945fc8e516682d2dd353e2802bfddc6
parent 8096f229421f7b22433775e928d506f0342e5907

bpf: Explicitly memset some bpf info structures declared on the stack

Trying to initialize a structure with "= {};" will not always clean out
all padding locations in a structure. So be explicit and call memset to
initialize everything for a number of bpf information structures that
are then copied from userspace, sometimes from smaller memory locations
than the size of the structure.

Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200320162258.GA794295@kroah.com

kernel/bpf/btf.c

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 32ab922..7787bdc 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -4564,7 +4564,7 @@
 		       union bpf_attr __user *uattr)
 {
 	struct bpf_btf_info __user *uinfo;
-	struct bpf_btf_info info = {};
+	struct bpf_btf_info info;
 	u32 info_copy, btf_copy;
 	void __user *ubtf;
 	u32 uinfo_len;
@@ -4573,6 +4573,7 @@
 	uinfo_len = attr->info.info_len;
 
 	info_copy = min_t(u32, uinfo_len, sizeof(info));
+	memset(&info, 0, sizeof(info));
 	if (copy_from_user(&info, uinfo, info_copy))
 		return -EFAULT;
 

kernel/bpf/syscall.c

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 3ac1629..966b7b3 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2795,7 +2795,7 @@
 				   union bpf_attr __user *uattr)
 {
 	struct bpf_prog_info __user *uinfo = u64_to_user_ptr(attr->info.info);
-	struct bpf_prog_info info = {};
+	struct bpf_prog_info info;
 	u32 info_len = attr->info.info_len;
 	struct bpf_prog_stats stats;
 	char __user *uinsns;
@@ -2807,6 +2807,7 @@
 		return err;
 	info_len = min_t(u32, sizeof(info), info_len);
 
+	memset(&info, 0, sizeof(info));
 	if (copy_from_user(&info, uinfo, info_len))
 		return -EFAULT;
 
@@ -3070,7 +3071,7 @@
 				  union bpf_attr __user *uattr)
 {
 	struct bpf_map_info __user *uinfo = u64_to_user_ptr(attr->info.info);
-	struct bpf_map_info info = {};
+	struct bpf_map_info info;
 	u32 info_len = attr->info.info_len;
 	int err;
 
@@ -3079,6 +3080,7 @@
 		return err;
 	info_len = min_t(u32, sizeof(info), info_len);
 
+	memset(&info, 0, sizeof(info));
 	info.type = map->map_type;
 	info.id = map->id;
 	info.key_size = map->key_size;