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From: Nick Piggin <npiggin@suse.de>
To: Andrew Morton <akpm@osdl.org>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
	Linux Filesystems <linux-fsdevel@vger.kernel.org>,
	Nick Piggin <npiggin@suse.de>,
	Linux Memory Management <linux-mm@kvack.org>
Subject: [patch 1/9] fs: libfs buffered write leak fix
Date: Mon, 29 Jan 2007 11:31:46 +0100 (CET)	[thread overview]
Message-ID: <20070129081914.23584.23886.sendpatchset@linux.site> (raw)
In-Reply-To: <20070129081905.23584.97878.sendpatchset@linux.site>

simple_prepare_write and nobh_prepare_write leak uninitialised kernel data.
Fix the former, make a note of the latter. Several other filesystems seem
to be iffy here, too.

Signed-off-by: Nick Piggin <npiggin@suse.de>

Index: linux-2.6/fs/libfs.c
===================================================================
--- linux-2.6.orig/fs/libfs.c
+++ linux-2.6/fs/libfs.c
@@ -327,32 +327,35 @@ int simple_readpage(struct file *file, s
 int simple_prepare_write(struct file *file, struct page *page,
 			unsigned from, unsigned to)
 {
-	if (!PageUptodate(page)) {
-		if (to - from != PAGE_CACHE_SIZE) {
-			void *kaddr = kmap_atomic(page, KM_USER0);
-			memset(kaddr, 0, from);
-			memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
-			flush_dcache_page(page);
-			kunmap_atomic(kaddr, KM_USER0);
-		}
+	if (PageUptodate(page))
+		return 0;
+
+	if (to - from != PAGE_CACHE_SIZE) {
+		clear_highpage(page);
+		flush_dcache_page(page);
 		SetPageUptodate(page);
 	}
+
 	return 0;
 }
 
 int simple_commit_write(struct file *file, struct page *page,
-			unsigned offset, unsigned to)
+			unsigned from, unsigned to)
 {
-	struct inode *inode = page->mapping->host;
-	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
-
-	/*
-	 * No need to use i_size_read() here, the i_size
-	 * cannot change under us because we hold the i_mutex.
-	 */
-	if (pos > inode->i_size)
-		i_size_write(inode, pos);
-	set_page_dirty(page);
+	if (to > from) {
+		struct inode *inode = page->mapping->host;
+		loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+
+		if (to - from == PAGE_CACHE_SIZE)
+			SetPageUptodate(page);
+		/*
+		 * No need to use i_size_read() here, the i_size
+		 * cannot change under us because we hold the i_mutex.
+		 */
+		if (pos > inode->i_size)
+			i_size_write(inode, pos);
+		set_page_dirty(page);
+	}
 	return 0;
 }
 
Index: linux-2.6/fs/buffer.c
===================================================================
--- linux-2.6.orig/fs/buffer.c
+++ linux-2.6/fs/buffer.c
@@ -2344,6 +2344,8 @@ int nobh_prepare_write(struct page *page
 
 	if (is_mapped_to_disk)
 		SetPageMappedToDisk(page);
+
+	/* XXX: information leak vs read(2) */
 	SetPageUptodate(page);
 
 	/*

  reply	other threads:[~2007-01-29 10:31 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-29 10:31 [patch 0/9] buffered write deadlock fix Nick Piggin
2007-01-29 10:31 ` Nick Piggin [this message]
2007-02-02 23:52   ` [patch 1/9] fs: libfs buffered write leak fix Andrew Morton
2007-02-03  1:33     ` Nick Piggin
2007-02-03  1:58       ` Andrew Morton
2007-02-03  2:09         ` Nick Piggin
2007-02-03  2:19           ` Andrew Morton
2007-02-03  2:28             ` Nick Piggin
2007-02-03 17:49       ` Jörn Engel
2007-02-04  3:55         ` Nick Piggin
2007-01-29 10:31 ` [patch 2/9] mm: revert "generic_file_buffered_write(): handle zero length iovec segments" Nick Piggin
2007-01-29 10:32 ` [patch 3/9] mm: revert "generic_file_buffered_write(): deadlock on vectored write" Nick Piggin
2007-01-29 10:32 ` [patch 4/9] mm: generic_file_buffered_write cleanup Nick Piggin
2007-01-29 10:32 ` [patch 5/9] mm: debug write deadlocks Nick Piggin
2007-01-29 10:32 ` [patch 6/9] mm: be sure to trim blocks Nick Piggin
2007-01-29 10:32 ` [patch 7/9] mm: cleanup pagecache insertion operations Nick Piggin
2007-01-29 10:32 ` [patch 8/9] mm: generic_file_buffered_write iovec cleanup Nick Piggin
2007-01-29 10:33 ` [patch 9/9] mm: fix pagecache write deadlocks Nick Piggin
2007-01-29 11:11   ` Nick Piggin
2007-02-02 23:53   ` Andrew Morton
2007-02-03  1:38     ` Nick Piggin
2007-01-30 20:55 ` [patch 0/9] buffered write deadlock fix Andrew Morton
2007-01-30 23:21   ` Andrew Morton
2007-01-31  1:31     ` Nick Piggin
2007-01-31  0:32   ` Nick Piggin
2007-02-02 23:52 ` Andrew Morton
2007-02-03  1:22   ` Nick Piggin
2007-02-03  6:43   ` Suparna Bhattacharya
     [not found]   ` <370516630.03363@ustc.edu.cn>
2007-02-03 15:31     ` Fengguang Wu
2007-02-04  8:49 Nick Piggin
2007-02-04  8:49 ` [patch 1/9] fs: libfs buffered write leak fix Nick Piggin

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