3.18-stable review patch. If anyone has any objections, please let me know.
------------------ From: Steve French <[email protected]> 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 <[email protected]> CC: Colin Ian King <[email protected]> Reviewed-by: Pavel Shilovsky <[email protected]> Reported-by: Eryu Guan <[email protected]> Signed-off-by: Ronnie Sahlberg <[email protected]> Signed-off-by: Steve French <[email protected]> Cc: [email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/cifs/dir.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/fs/cifs/dir.c +++ b/fs/cifs/dir.c @@ -674,6 +674,9 @@ 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; @@ -682,10 +685,8 @@ 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)) @@ -732,7 +733,7 @@ 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);
