From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , Jeff Mahoney , Eric Biggers , Al Viro , Andrew Morton , Linus Torvalds Subject: [PATCH 4.4 79/79] reiserfs: fix broken xattr handling (heap corruption, bad retval) Date: Thu, 23 Aug 2018 09:53:55 +0200 Message-Id: <20180823074924.369245762@linuxfoundation.org> In-Reply-To: <20180823074918.641878835@linuxfoundation.org> References: <20180823074918.641878835@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit a13f085d111e90469faf2d9965eb39b11c114d7e upstream. This fixes the following issues: - When a buffer size is supplied to reiserfs_listxattr() such that each individual name fits, but the concatenation of all names doesn't fit, reiserfs_listxattr() overflows the supplied buffer. This leads to a kernel heap overflow (verified using KASAN) followed by an out-of-bounds usercopy and is therefore a security bug. - When a buffer size is supplied to reiserfs_listxattr() such that a name doesn't fit, -ERANGE should be returned. But reiserfs instead just truncates the list of names; I have verified that if the only xattr on a file has a longer name than the supplied buffer length, listxattr() incorrectly returns zero. With my patch applied, -ERANGE is returned in both cases and the memory corruption doesn't happen anymore. Credit for making me clean this code up a bit goes to Al Viro, who pointed out that the ->actor calling convention is suboptimal and should be changed. Link: http://lkml.kernel.org/r/20180802151539.5373-1-jannh@google.com Fixes: 48b32a3553a5 ("reiserfs: use generic xattr handlers") Signed-off-by: Jann Horn Acked-by: Jeff Mahoney Cc: Eric Biggers Cc: Al Viro Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/reiserfs/xattr.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/fs/reiserfs/xattr.c +++ b/fs/reiserfs/xattr.c @@ -791,8 +791,10 @@ static int listxattr_filler(struct dir_c size = handler->list(handler, b->dentry, b->buf + b->pos, b->size, name, namelen); - if (size > b->size) + if (b->pos + size > b->size) { + b->pos = -ERANGE; return -ERANGE; + } } else { size = handler->list(handler, b->dentry, NULL, 0, name, namelen);