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

BugLink: https://bugs.launchpad.net/bugs/1870604
commit 5c6f25887963f15492b604dd25cb149c501bbabf upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 3fe26282bd2c10f5ed04a6307150122e4d59735e..dde49a2bd541d910f5aedecabe5cafb22194ffa2 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1596,7 +1596,7 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
                                   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;
        char __user *uinsns;
        u32 ulen;
@@ -1607,6 +1607,7 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
                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;
 
@@ -1669,7 +1670,7 @@ static int bpf_map_get_info_by_fd(struct bpf_map *map,
                                  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;
 
@@ -1678,6 +1679,7 @@ static int bpf_map_get_info_by_fd(struct bpf_map *map,
                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;