linux-kernel - [PATCH] hpfs: don't truncate the file when delete fails

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.DEB.2.00.1602251800130.10262@leontynka>
Date:	Thu, 25 Feb 2016 18:17:38 +0100 (CET)
From:	Mikulas Patocka <mikulas@...bright.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
cc:	Al Viro <viro@...IV.linux.org.uk>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] hpfs: don't truncate the file when delete fails

The delete opration can allocate additional space on the HPFS filesystem
due to btree split. The HPFS driver checks in advance if there is
available space, so that it won't corrupt the btree if we run out of space
during splitting.

If there is not enough available space, the HPFS driver attempted to
truncate the file, but this results in a deadlock since the commit
7dd29d8d865efdb00c0542a5d2c87af8c52ea6c7 ("HPFS: Introduce a global mutex
and lock it on every callback from VFS").

This patch removes the code that tries to truncate the file and -ENOSPC is
returned instead. If the user hits -ENOSPC on delete, he should try to
delete other files (that are stored in a leaf btree node), so that the
delete operation will make some space for deleting the file stored in
non-leaf btree node.

Reported-by: Al Viro <viro@...IV.linux.org.uk>
Signed-off-by: Mikulas Patocka <mikulas@...ax.karlin.mff.cuni.cz>
Cc: stable@...r.kernel.org	# 2.6.39+

Index: linux-4.4.2/fs/hpfs/namei.c
===================================================================
--- linux-4.4.2.orig/fs/hpfs/namei.c
+++ linux-4.4.2/fs/hpfs/namei.c
@@ -375,12 +375,11 @@ static int hpfs_unlink(struct inode *dir
 	struct inode *inode = d_inode(dentry);
 	dnode_secno dno;
 	int r;
-	int rep = 0;
 	int err;
 
 	hpfs_lock(dir->i_sb);
 	hpfs_adjust_length(name, &len);
-again:
+
 	err = -ENOENT;
 	de = map_dirent(dir, hpfs_i(dir)->i_dno, name, len, &dno, &qbh);
 	if (!de)
@@ -400,33 +399,9 @@ again:
 		hpfs_error(dir->i_sb, "there was error when removing dirent");
 		err = -EFSERROR;
 		break;
-	case 2:		/* no space for deleting, try to truncate file */
-
+	case 2:		/* no space for deleting */
 		err = -ENOSPC;
-		if (rep++)
-			break;
-
-		dentry_unhash(dentry);
-		if (!d_unhashed(dentry)) {
-			hpfs_unlock(dir->i_sb);
-			return -ENOSPC;
-		}
-		if (generic_permission(inode, MAY_WRITE) ||
-		    !S_ISREG(inode->i_mode) ||
-		    get_write_access(inode)) {
-			d_rehash(dentry);
-		} else {
-			struct iattr newattrs;
-			/*pr_info("truncating file before delete.\n");*/
-			newattrs.ia_size = 0;
-			newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
-			err = notify_change(dentry, &newattrs, NULL);
-			put_write_access(inode);
-			if (!err)
-				goto again;
-		}
-		hpfs_unlock(dir->i_sb);
-		return -ENOSPC;
+		break;
 	default:
 		drop_nlink(inode);
 		err = 0;