4.16-stable review patch. If anyone has any objections, please let me know.
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From: Steve French smfrench@gmail.com
commit 1d0cffa674cfa7d185a302c8c6850fc50b893bed upstream.
RHBZ: 1453123
Since at least the 3.10 kernel and likely a lot earlier we have not been able to create unix domain sockets in a cifs share when mounted using the SFU mount option (except when mounted with the cifs unix extensions to Samba e.g.) Trying to create a socket, for example using the af_unix command from xfstests will cause : BUG: unable to handle kernel NULL pointer dereference at 00000000 00000040
Since no one uses or depends on being able to create unix domains sockets on a cifs share the easiest fix to stop this vulnerability is to simply not allow creation of any other special files than char or block devices when sfu is used.
Added update to Ronnie's patch to handle a tcon link leak, and to address a buf leak noticed by Gustavo and Colin.
Acked-by: Gustavo A. R. Silva gustavo@embeddedor.com CC: Colin Ian King colin.king@canonical.com Reviewed-by: Pavel Shilovsky pshilov@microsoft.com Reported-by: Eryu Guan eguan@redhat.com Signed-off-by: Ronnie Sahlberg lsahlber@redhat.com Signed-off-by: Steve French smfrench@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/cifs/dir.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
--- a/fs/cifs/dir.c +++ b/fs/cifs/dir.c @@ -684,6 +684,9 @@ int cifs_mknod(struct inode *inode, stru goto mknod_out; }
+ if (!S_ISCHR(mode) && !S_ISBLK(mode)) + goto mknod_out; + if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL)) goto mknod_out;
@@ -692,10 +695,8 @@ int cifs_mknod(struct inode *inode, stru
buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL); if (buf == NULL) { - kfree(full_path); rc = -ENOMEM; - free_xid(xid); - return rc; + goto mknod_out; }
if (backup_cred(cifs_sb)) @@ -742,7 +743,7 @@ int cifs_mknod(struct inode *inode, stru pdev->minor = cpu_to_le64(MINOR(device_number)); rc = tcon->ses->server->ops->sync_write(xid, &fid, &io_parms, &bytes_written, iov, 1); - } /* else if (S_ISFIFO) */ + } tcon->ses->server->ops->close(xid, tcon, &fid); d_drop(direntry);