fix deadlock in cifs_ioctl_clone()

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commit 378ff1a53b 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>

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Al Viro 2015-01-18 23:37:32 -05:00 • committed by Luis Henriques

parent a4fe814c49

commit 0fd895b331

1 changed files with 5 additions and 16 deletions

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fs/cifs/ioctl.c

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