Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755331AbbF0BJb (ORCPT ); Fri, 26 Jun 2015 21:09:31 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:47367 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752644AbbF0BIj (ORCPT ); Fri, 26 Jun 2015 21:08:39 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ben Hutchings Subject: [PATCH 3.10 4/5] pipe: iovec: Fix memory corruption when retrying atomic copy as non-atomic Date: Fri, 26 Jun 2015 18:08:27 -0700 Message-Id: <20150627010806.481761134@linuxfoundation.org> X-Mailer: git-send-email 2.4.4 In-Reply-To: <20150627010806.352473049@linuxfoundation.org> References: <20150627010806.352473049@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5585 Lines: 186 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings pipe_iov_copy_{from,to}_user() may be tried twice with the same iovec, the first time atomically and the second time not. The second attempt needs to continue from the iovec position, pipe buffer offset and remaining length where the first attempt failed, but currently the pipe buffer offset and remaining length are reset. This will corrupt the piped data (possibly also leading to an information leak between processes) and may also corrupt kernel memory. This was fixed upstream by commits f0d1bec9d58d ("new helper: copy_page_from_iter()") and 637b58c2887e ("switch pipe_read() to copy_page_to_iter()"), but those aren't suitable for stable. This fix for older kernel versions was made by Seth Jennings for RHEL and I have extracted it from their update. CVE-2015-1805 References: https://bugzilla.redhat.com/show_bug.cgi?id=1202855 Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- fs/pipe.c | 55 ++++++++++++++++++++++++++++++++----------------------- 1 file changed, 32 insertions(+), 23 deletions(-) --- a/fs/pipe.c +++ b/fs/pipe.c @@ -117,25 +117,27 @@ void pipe_wait(struct pipe_inode_info *p } static int -pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len, - int atomic) +pipe_iov_copy_from_user(void *addr, int *offset, struct iovec *iov, + size_t *remaining, int atomic) { unsigned long copy; - while (len > 0) { + while (*remaining > 0) { while (!iov->iov_len) iov++; - copy = min_t(unsigned long, len, iov->iov_len); + copy = min_t(unsigned long, *remaining, iov->iov_len); if (atomic) { - if (__copy_from_user_inatomic(to, iov->iov_base, copy)) + if (__copy_from_user_inatomic(addr + *offset, + iov->iov_base, copy)) return -EFAULT; } else { - if (copy_from_user(to, iov->iov_base, copy)) + if (copy_from_user(addr + *offset, + iov->iov_base, copy)) return -EFAULT; } - to += copy; - len -= copy; + *offset += copy; + *remaining -= copy; iov->iov_base += copy; iov->iov_len -= copy; } @@ -143,25 +145,27 @@ pipe_iov_copy_from_user(void *to, struct } static int -pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len, - int atomic) +pipe_iov_copy_to_user(struct iovec *iov, void *addr, int *offset, + size_t *remaining, int atomic) { unsigned long copy; - while (len > 0) { + while (*remaining > 0) { while (!iov->iov_len) iov++; - copy = min_t(unsigned long, len, iov->iov_len); + copy = min_t(unsigned long, *remaining, iov->iov_len); if (atomic) { - if (__copy_to_user_inatomic(iov->iov_base, from, copy)) + if (__copy_to_user_inatomic(iov->iov_base, + addr + *offset, copy)) return -EFAULT; } else { - if (copy_to_user(iov->iov_base, from, copy)) + if (copy_to_user(iov->iov_base, + addr + *offset, copy)) return -EFAULT; } - from += copy; - len -= copy; + *offset += copy; + *remaining -= copy; iov->iov_base += copy; iov->iov_len -= copy; } @@ -395,7 +399,7 @@ pipe_read(struct kiocb *iocb, const stru struct pipe_buffer *buf = pipe->bufs + curbuf; const struct pipe_buf_operations *ops = buf->ops; void *addr; - size_t chars = buf->len; + size_t chars = buf->len, remaining; int error, atomic; if (chars > total_len) @@ -409,9 +413,11 @@ pipe_read(struct kiocb *iocb, const stru } atomic = !iov_fault_in_pages_write(iov, chars); + remaining = chars; redo: addr = ops->map(pipe, buf, atomic); - error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic); + error = pipe_iov_copy_to_user(iov, addr, &buf->offset, + &remaining, atomic); ops->unmap(pipe, buf, addr); if (unlikely(error)) { /* @@ -426,7 +432,6 @@ redo: break; } ret += chars; - buf->offset += chars; buf->len -= chars; /* Was it a packet buffer? Clean up and exit */ @@ -531,6 +536,7 @@ pipe_write(struct kiocb *iocb, const str if (ops->can_merge && offset + chars <= PAGE_SIZE) { int error, atomic = 1; void *addr; + size_t remaining = chars; error = ops->confirm(pipe, buf); if (error) @@ -539,8 +545,8 @@ pipe_write(struct kiocb *iocb, const str iov_fault_in_pages_read(iov, chars); redo1: addr = ops->map(pipe, buf, atomic); - error = pipe_iov_copy_from_user(offset + addr, iov, - chars, atomic); + error = pipe_iov_copy_from_user(addr, &offset, iov, + &remaining, atomic); ops->unmap(pipe, buf, addr); ret = error; do_wakeup = 1; @@ -575,6 +581,8 @@ redo1: struct page *page = pipe->tmp_page; char *src; int error, atomic = 1; + int offset = 0; + size_t remaining; if (!page) { page = alloc_page(GFP_HIGHUSER); @@ -595,14 +603,15 @@ redo1: chars = total_len; iov_fault_in_pages_read(iov, chars); + remaining = chars; redo2: if (atomic) src = kmap_atomic(page); else src = kmap(page); - error = pipe_iov_copy_from_user(src, iov, chars, - atomic); + error = pipe_iov_copy_from_user(src, &offset, iov, + &remaining, atomic); if (atomic) kunmap_atomic(src); else -- 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/