Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756746Ab3CZXGr (ORCPT ); Tue, 26 Mar 2013 19:06:47 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53448 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756865Ab3CZXCQ (ORCPT ); Tue, 26 Mar 2013 19:02:16 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Linus Torvalds , Al Viro , Mathieu Desnoyers Subject: [ 43/49] Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys Date: Tue, 26 Mar 2013 16:01:40 -0700 Message-Id: <20130326225844.034895114@linuxfoundation.org> X-Mailer: git-send-email 1.8.1.rc1.5.g7e0651a In-Reply-To: <20130326225839.554028294@linuxfoundation.org> References: <20130326225839.554028294@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3631 Lines: 108 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mathieu Desnoyers commit 8aec0f5d4137532de14e6554fd5dd201ff3a3c49 upstream. Looking at mm/process_vm_access.c:process_vm_rw() and comparing it to compat_process_vm_rw() shows that the compatibility code requires an explicit "access_ok()" check before calling compat_rw_copy_check_uvector(). The same difference seems to appear when we compare fs/read_write.c:do_readv_writev() to fs/compat.c:compat_do_readv_writev(). This subtle difference between the compat and non-compat requirements should probably be debated, as it seems to be error-prone. In fact, there are two others sites that use this function in the Linux kernel, and they both seem to get it wrong: Now shifting our attention to fs/aio.c, we see that aio_setup_iocb() also ends up calling compat_rw_copy_check_uvector() through aio_setup_vectored_rw(). Unfortunately, the access_ok() check appears to be missing. Same situation for security/keys/compat.c:compat_keyctl_instantiate_key_iov(). I propose that we add the access_ok() check directly into compat_rw_copy_check_uvector(), so callers don't have to worry about it, and it therefore makes the compat call code similar to its non-compat counterpart. Place the access_ok() check in the same location where copy_from_user() can trigger a -EFAULT error in the non-compat code, so the ABI behaviors are alike on both compat and non-compat. While we are here, fix compat_do_readv_writev() so it checks for compat_rw_copy_check_uvector() negative return values. And also, fix a memory leak in compat_keyctl_instantiate_key_iov() error handling. Acked-by: Linus Torvalds Acked-by: Al Viro Signed-off-by: Mathieu Desnoyers Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/compat.c | 15 +++++++-------- security/keys/compat.c | 4 ++-- 2 files changed, 9 insertions(+), 10 deletions(-) --- a/fs/compat.c +++ b/fs/compat.c @@ -576,6 +576,10 @@ ssize_t compat_rw_copy_check_uvector(int } *ret_pointer = iov; + ret = -EFAULT; + if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector))) + goto out; + /* * Single unix specification: * We should -EINVAL if an element length is not >= 0 and fitting an @@ -1106,17 +1110,12 @@ static ssize_t compat_do_readv_writev(in if (!file->f_op) goto out; - ret = -EFAULT; - if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector))) - goto out; - - tot_len = compat_rw_copy_check_uvector(type, uvector, nr_segs, + ret = compat_rw_copy_check_uvector(type, uvector, nr_segs, UIO_FASTIOV, iovstack, &iov); - if (tot_len == 0) { - ret = 0; + if (ret <= 0) goto out; - } + tot_len = ret; ret = rw_verify_area(type, file, pos, tot_len); if (ret < 0) goto out; --- a/security/keys/compat.c +++ b/security/keys/compat.c @@ -40,12 +40,12 @@ long compat_keyctl_instantiate_key_iov( ARRAY_SIZE(iovstack), iovstack, &iov); if (ret < 0) - return ret; + goto err; if (ret == 0) goto no_payload_free; ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid); - +err: if (iov != iovstack) kfree(iov); return ret; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/