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authorJann Horn <jann@thejh.net>2015-09-11 16:27:27 +0200
committerSteve French <smfrench@gmail.com>2015-09-11 09:54:03 -0500
commit4c17a6d56bb0cad3066a714e94f7185a24b40f49 (patch)
treecbd5fe9b42e01ef05f8e4fa0298c0a82c2180d44
parentb0a1ea51bda4c2bcdde460221e1772f3a4f8c44f (diff)
downloadlinux-4c17a6d56bb0cad3066a714e94f7185a24b40f49.tar.bz2
CIFS: fix type confusion in copy offload ioctl
This might lead to local privilege escalation (code execution as kernel) for systems where the following conditions are met: - CONFIG_CIFS_SMB2 and CONFIG_CIFS_POSIX are enabled - a cifs filesystem is mounted where: - the mount option "vers" was used and set to a value >=2.0 - the attacker has write access to at least one file on the filesystem To attack this, an attacker would have to guess the target_tcon pointer (but guessing wrong doesn't cause a crash, it just returns an error code) and win a narrow race. CC: Stable <stable@vger.kernel.org> Signed-off-by: Jann Horn <jann@thejh.net> Signed-off-by: Steve French <smfrench@gmail.com>
-rw-r--r--fs/cifs/ioctl.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c
index c63f5227b681..28a77bf1d559 100644
--- a/fs/cifs/ioctl.c
+++ b/fs/cifs/ioctl.c
@@ -67,6 +67,12 @@ static long cifs_ioctl_clone(unsigned int xid, struct file *dst_file,
goto out_drop_write;
}
+ if (src_file.file->f_op->unlocked_ioctl != cifs_ioctl) {
+ rc = -EBADF;
+ cifs_dbg(VFS, "src file seems to be from a different filesystem type\n");
+ goto out_fput;
+ }
+
if ((!src_file.file->private_data) || (!dst_file->private_data)) {
rc = -EBADF;
cifs_dbg(VFS, "missing cifsFileInfo on copy range src file\n");