mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-28 05:12:49 +00:00
Code Issues Releases Wiki Activity

make sure that __dentry_kill() always invalidates d_seq, unhashed or not

Browse source 
commit 4c0d7cd5c8 upstream.

RCU pathwalk relies upon the assumption that anything that changes
->d_inode of a dentry will invalidate its ->d_seq.  That's almost
true - the one exception is that the final dput() of already unhashed
dentry does *not* touch ->d_seq at all.  Unhashing does, though,
so for anything we'd found by RCU dcache lookup we are fine.
Unfortunately, we can *start* with an unhashed dentry or jump into
it.

We could try and be careful in the (few) places where that could
happen.  Or we could just make the final dput() invalidate the damn
thing, unhashed or not.  The latter is much simpler and easier to
backport, so let's do it that way.

Reported-by: "Dae R. Jeong" <threeearcat@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Al Viro 2018-08-09 10:15:54 -04:00 committed by Greg Kroah-Hartman
parent cfac7df7dc
commit 59199c04b7
1 changed files with 2 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
fs/dcache.c
View file

@ -352,14 +352,11 @@ static void dentry_unlink_inode(struct dentry * dentry)
__releases(dentry->d_inode->i_lock)
{
struct inode *inode = dentry->d_inode;
bool hashed = !d_unhashed(dentry);
if (hashed)
raw_write_seqcount_begin(&dentry->d_seq);
raw_write_seqcount_begin(&dentry->d_seq);
__d_clear_type_and_inode(dentry);
hlist_del_init(&dentry->d_u.d_alias);
if (hashed)
raw_write_seqcount_end(&dentry->d_seq);
raw_write_seqcount_end(&dentry->d_seq);
spin_unlock(&dentry->d_lock);
spin_unlock(&inode->i_lock);
if (!inode->i_nlink)