Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759409AbbLBR0v (ORCPT ); Wed, 2 Dec 2015 12:26:51 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:43826 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933268AbbLBRBi (ORCPT ); Wed, 2 Dec 2015 12:01:38 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Biggers , Al Viro , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 115/164] fs/pipe.c: return error code rather than 0 in pipe_write() Date: Wed, 2 Dec 2015 08:59:26 -0800 Message-Id: <1449075615-20754-116-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1449075615-20754-1-git-send-email-kamal@canonical.com> References: <1449075615-20754-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2118 Lines: 78 3.19.8-ckt11 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers commit 6ae08069939f17422835448acae76bda8d96b16a upstream. pipe_write() would return 0 if it failed to merge the beginning of the data to write with the last, partially filled pipe buffer. It should return an error code instead. Userspace programs could be confused by write() returning 0 when called with a nonzero 'count'. The EFAULT error case was a regression from f0d1bec9d5 ("new helper: copy_page_from_iter()"), while the ops->confirm() error case was a much older bug. Test program: #include #include #include int main(void) { int fd[2]; char data[1] = {0}; assert(0 == pipe(fd)); assert(1 == write(fd[1], data, 1)); /* prior to this patch, write() returned 0 here */ assert(-1 == write(fd[1], NULL, 1)); assert(errno == EFAULT); } Signed-off-by: Eric Biggers Signed-off-by: Al Viro Signed-off-by: Kamal Mostafa --- fs/pipe.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/pipe.c b/fs/pipe.c index 21981e5..6c856a1 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -367,18 +367,17 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) int offset = buf->offset + buf->len; if (ops->can_merge && offset + chars <= PAGE_SIZE) { - int error = ops->confirm(pipe, buf); - if (error) + ret = ops->confirm(pipe, buf); + if (ret) goto out; ret = copy_page_from_iter(buf->page, offset, chars, from); if (unlikely(ret < chars)) { - error = -EFAULT; + ret = -EFAULT; goto out; } do_wakeup = 1; - buf->len += chars; - ret = chars; + buf->len += ret; if (!iov_iter_count(from)) goto out; } -- 1.9.1 -- 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/