On Wed May 11, 2011 at 05:08:45PM -0400, Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> wrote: > On Wed, 2011-05-11 at 17:03 -0400, Peng Huang wrote: > > lookup_one_len() may call nfs_loopup_revalidate() with nd == NULL > > indirectly, that causes the kernel crash. > > > > RIP: 0010:[<ffffffffa0ba3b41>] [<ffffffffa0ba3b41>] > > nfs_lookup_revalidate+0x21/0x4a0 [nfs] > > RSP: 0018:ffff88018f00fae8 EFLAGS: 00010286 > > > > Call Trace: > > [<ffffffff81164a17>] do_revalidate+0x17/0x60 > > [<ffffffff81164e9b>] __lookup_hash+0xcb/0x140 > > [<ffffffff811653c4>] lookup_one_len+0x94/0xe0 > > [<ffffffff81241ef1>] ecryptfs_lookup+0x91/0x1d0 > > [<ffffffff81164d85>] d_alloc_and_lookup+0x45/0x90 > > [<ffffffff8116f7b5>] ? d_lookup+0x35/0x60 > > [<ffffffff811669b2>] do_lookup+0x192/0x2d0 > > [<ffffffff811763be>] ? vfsmount_lock_local_unlock+0x1e/0x30 > > [<ffffffff8126d09c>] ? security_inode_permission+0x1c/0x30 > > [<ffffffff81167d67>] link_path_walk+0x597/0xae0 > > [<ffffffff8117638e>] ? vfsmount_lock_local_lock+0x1e/0x30 > > [<ffffffff81165905>] ? path_init_rcu+0xa5/0x210 > > [<ffffffff8116858b>] do_path_lookup+0x5b/0x140 > > [<ffffffff811692f7>] user_path_at+0x57/0xa0 > > [<ffffffff8159fd08>] ? do_page_fault+0x1e8/0x4e0 > > [<ffffffff8115eb86>] vfs_fstatat+0x46/0x80 > > [<ffffffff8116b990>] ? filldir+0x0/0xe0 > > [<ffffffff8115ec2e>] vfs_lstat+0x1e/0x20 > > [<ffffffff8115ec54>] sys_newlstat+0x24/0x50 > > [<ffffffff8159c995>] ? page_fault+0x25/0x30 > > [<ffffffff8100bfc2>] system_call_fastpath+0x16/0x1b > > > > Signed-off-by: Peng Huang <shawn.p.huang@xxxxxxxxx> > > --- > > fs/nfs/dir.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c > > index 2c3eb33..9452aa5 100644 > > --- a/fs/nfs/dir.c > > +++ b/fs/nfs/dir.c > > @@ -1028,7 +1028,7 @@ static int nfs_lookup_revalidate(struct dentry *dentry, struct nameidata *nd) > > struct nfs_fattr *fattr = NULL; > > int error; > > > > - if (nd->flags & LOOKUP_RCU) > > + if (nd != NULL && nd->flags & LOOKUP_RCU) > > return -ECHILD; > > > > parent = dget_parent(dentry); > > That's exactly what Tyler Hicks proposed last week and which was NACKed. > We simply won't support layered filesystems that don't do intents. But you _did_ support it up until 34286d66 "fs: rcu-walk aware d_revalidate method" I see why you wouldn't want NULL nameidata in the NFSv4 specific functions, but don't quite understand the opposition against it in NFSv3 (nfs_lookup_revalidate). The one-liner above would allow users to begin using eCryptfs on top of NFSv3 clients immediately, with no side effects to NFS. Tyler > > IOW: Feel free to change the above to. > > if (nd == NULL) > return -EIO; > > > > > -- > Trond Myklebust > Linux NFS client maintainer > > NetApp > Trond.Myklebust@xxxxxxxxxx > www.netapp.com > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
