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 2616424012ea7bf4bc7f87a935466c74bb267397..4960c69cc47cf9baf4f5c8a998fe6fcb80d94d90 100644 (file)
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -128,6 +128,7 @@ 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) &
@@ -156,7 +157,6 @@ 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;
@@ -169,6 +169,7 @@ 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;
@@ -180,7 +181,6 @@ 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;