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Commit 6d09bb62 authored by Trond Myklebust's avatar Trond Myklebust Committed by Linus Torvalds
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[PATCH] fs/namei.c: Call to file_permission() under a spinlock in do_lookup_path() 



From: Trond Myklebust <Trond.Myklebust@netapp.com>

We're presently running lock_kernel() under fs_lock via nfs's ->permission
handler.  That's a ranking bug and sometimes a sleep-in-spinlock bug.  This
problem was introduced in the openat() patchset.

We should not need to hold the current->fs->lock for a codepath that doesn't
use current->fs.

[vsu@altlinux.ru: fix error path]
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Signed-off-by: default avatarSergey Vlasov <vsu@altlinux.ru>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c7d2d28b

fs/namei.c

+10 −9
Original line number Diff line number Diff line
@@ -1080,8 +1080,8 @@ static int fastcall do_path_lookup(int dfd, const char *name, 
	nd->flags = flags;

	nd->depth = 0;



	read_lock(&current->fs->lock);

	if (*name=='/') {

		read_lock(&current->fs->lock);

		if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {

			nd->mnt = mntget(current->fs->altrootmnt);

			nd->dentry = dget(current->fs->altroot);
@@ -1092,33 +1092,35 @@ static int fastcall do_path_lookup(int dfd, const char *name, 
		}

		nd->mnt = mntget(current->fs->rootmnt);

		nd->dentry = dget(current->fs->root);

		read_unlock(&current->fs->lock);

	} else if (dfd == AT_FDCWD) {

		read_lock(&current->fs->lock);

		nd->mnt = mntget(current->fs->pwdmnt);

		nd->dentry = dget(current->fs->pwd);

		read_unlock(&current->fs->lock);

	} else {

		struct dentry *dentry;



		file = fget_light(dfd, &fput_needed);

		retval = -EBADF;

		if (!file)

			goto unlock_fail;

			goto out_fail;



		dentry = file->f_dentry;



		retval = -ENOTDIR;

		if (!S_ISDIR(dentry->d_inode->i_mode))

			goto fput_unlock_fail;

			goto fput_fail;



		retval = file_permission(file, MAY_EXEC);

		if (retval)

			goto fput_unlock_fail;

			goto fput_fail;



		nd->mnt = mntget(file->f_vfsmnt);

		nd->dentry = dget(dentry);



		fput_light(file, fput_needed);

	}

	read_unlock(&current->fs->lock);

	current->total_link_count = 0;

	retval = link_path_walk(name, nd);

out:
@@ -1127,13 +1129,12 @@ static int fastcall do_path_lookup(int dfd, const char *name, 
				nd->dentry->d_inode))

		audit_inode(name, nd->dentry->d_inode, flags);

	}

out_fail:

	return retval;



fput_unlock_fail:

fput_fail:

	fput_light(file, fput_needed);

unlock_fail:

	read_unlock(&current->fs->lock);

	return retval;

	goto out_fail;

}



int fastcall path_lookup(const char *name, unsigned int flags,