From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757011Ab3CNKkF (ORCPT ); Thu, 14 Mar 2013 06:40:05 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52106 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756757Ab3CNKiV (ORCPT ); Thu, 14 Mar 2013 06:38:21 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Mathieu Desnoyers , Linus Torvalds , Luis Henriques Subject: [PATCH 82/88] Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys Date: Thu, 14 Mar 2013 10:36:15 +0000 Message-Id: <1363257381-15900-83-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1363257381-15900-1-git-send-email-luis.henriques@canonical.com> References: <1363257381-15900-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.5.7.8 -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: Luis Henriques --- fs/compat.c | 15 +++++++-------- mm/process_vm_access.c | 8 -------- security/keys/compat.c | 4 ++-- 3 files changed, 9 insertions(+), 18 deletions(-) diff --git a/fs/compat.c b/fs/compat.c index 1bdb350..8e8461e 100644 --- a/fs/compat.c +++ b/fs/compat.c @@ -558,6 +558,10 @@ ssize_t compat_rw_copy_check_uvector(int type, } *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 @@ -1084,17 +1088,12 @@ static ssize_t compat_do_readv_writev(int type, struct file *file, 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; diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c index 926b466..fd26d04 100644 --- a/mm/process_vm_access.c +++ b/mm/process_vm_access.c @@ -429,12 +429,6 @@ compat_process_vm_rw(compat_pid_t pid, if (flags != 0) return -EINVAL; - if (!access_ok(VERIFY_READ, lvec, liovcnt * sizeof(*lvec))) - goto out; - - if (!access_ok(VERIFY_READ, rvec, riovcnt * sizeof(*rvec))) - goto out; - if (vm_write) rc = compat_rw_copy_check_uvector(WRITE, lvec, liovcnt, UIO_FASTIOV, iovstack_l, @@ -459,8 +453,6 @@ free_iovecs: kfree(iov_r); if (iov_l != iovstack_l) kfree(iov_l); - -out: return rc; } diff --git a/security/keys/compat.c b/security/keys/compat.c index c92d42b..803525f 100644 --- 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; -- 1.8.1.2