statfs: enforce statfs[64] structure initialization

commit ed40866ec7d328b3dfb70db7e2011640a16202c3 upstream.

s390's struct statfs and struct statfs64 contain padding, which
field-by-field copying does not set. Initialize the respective structs
with zeros before filling them and copying them to userspace, like it's
already done for the compat versions of these structs.

Found by KMSAN.

[agordeev@linux.ibm.com: fixed typo in patch description]
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20230504144021.808932-2-iii@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/statfs.c b/fs/statfs.c
index ca1084cbe03cfb5fc2dc1df649a195af5f168523..e6ceb3e8774f666985172c7067d3e4dc7e45a900 100644 (file)
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -114,6 +114,7 @@ static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
        if (sizeof(buf) == sizeof(*st))
                memcpy(&buf, st, sizeof(*st));
        else {
+               memset(&buf, 0, sizeof(buf));
                if (sizeof buf.f_blocks == 4) {
                        if ((st->f_blocks | st->f_bfree | st->f_bavail |
                             st->f_bsize | st->f_frsize) &
@@ -142,7 +143,6 @@ static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
                buf.f_namelen = st->f_namelen;
                buf.f_frsize = st->f_frsize;
                buf.f_flags = st->f_flags;
-               memset(buf.f_spare, 0, sizeof(buf.f_spare));
        }
        if (copy_to_user(p, &buf, sizeof(buf)))
                return -EFAULT;
@@ -155,6 +155,7 @@ static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
        if (sizeof(buf) == sizeof(*st))
                memcpy(&buf, st, sizeof(*st));
        else {
+               memset(&buf, 0, sizeof(buf));
                buf.f_type = st->f_type;
                buf.f_bsize = st->f_bsize;
                buf.f_blocks = st->f_blocks;
@@ -166,7 +167,6 @@ static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
                buf.f_namelen = st->f_namelen;
                buf.f_frsize = st->f_frsize;
                buf.f_flags = st->f_flags;
-               memset(buf.f_spare, 0, sizeof(buf.f_spare));
        }
        if (copy_to_user(p, &buf, sizeof(buf)))
                return -EFAULT;