@@ -86,21 +86,16 @@ static long cifs_ioctl_clone(unsigned int xid, struct file *dst_file,
}
src_inode = file_inode(src_file.file);
+ rc = -EINVAL;
+ if (S_ISDIR(src_inode->i_mode))
+ goto out_fput;
/*
* Note: cifs case is easier than btrfs since server responsible for
* checks for proper open modes and file type and if it wants
* server could even support copy of range where source = target
*/
-
- /* so we do not deadlock racing two ioctls on same files */
- if (target_inode < src_inode) {
- mutex_lock_nested(&target_inode->i_mutex, I_MUTEX_PARENT);
- mutex_lock_nested(&src_inode->i_mutex, I_MUTEX_CHILD);
- } else {
- mutex_lock_nested(&src_inode->i_mutex, I_MUTEX_PARENT);
- mutex_lock_nested(&target_inode->i_mutex, I_MUTEX_CHILD);
- }
+ lock_two_nondirectories(target_inode, src_inode);
/* determine range to clone */
rc = -EINVAL;
@@ -124,13 +119,7 @@ static long cifs_ioctl_clone(unsigned int xid, struct file *dst_file,
out_unlock:
/* although unlocking in the reverse order from locking is not
strictly necessary here it is a little cleaner to be consistent */
- if (target_inode < src_inode) {
- mutex_unlock(&src_inode->i_mutex);
- mutex_unlock(&target_inode->i_mutex);
- } else {
- mutex_unlock(&target_inode->i_mutex);
- mutex_unlock(&src_inode->i_mutex);
- }
+ unlock_two_nondirectories(src_inode, target_inode);
out_fput:
fdput(src_file);
out_drop_write:
This is a note to let you know that I have just added a patch titled fix deadlock in cifs_ioctl_clone() to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt6. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 7562422faed7366b6e0b72610ba0d7c01fbfacc4 Mon Sep 17 00:00:00 2001 From: Al Viro <viro@zeniv.linux.org.uk> Date: Sun, 18 Jan 2015 23:37:32 -0500 Subject: fix deadlock in cifs_ioctl_clone() commit 378ff1a53b5724f3ac97b0aba3c9ecac072f6fcd upstream. It really needs to check that src is non-directory *and* use {un,}lock_two_nodirectories(). As it is, it's trivial to cause double-lock (ioctl(fd, CIFS_IOC_COPYCHUNK_FILE, fd)) and if the last argument is an fd of directory, we are asking for trouble by violating the locking order - all directories go before all non-directories. If the last argument is an fd of parent directory, it has 50% odds of locking child before parent, which will cause AB-BA deadlock if we race with unlink(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- fs/cifs/ioctl.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-) -- 2.1.4