The patch titled
vfs: don't call attach_nobh_buffers() with an empty list
has been added to the -mm tree. Its filename is
vfs-dont-call-attach_nobh_buffers-with-an-empty-list.patch
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------------------------------------------------------
Subject: vfs: don't call attach_nobh_buffers() with an empty list
From: Dave Kleikamp <shaggy@xxxxxxxxxxxxxxxxxx>
This is a modification of a patch by Bill Pemberton.
nobh_write_end() could call attach_nobh_buffers() with head == NULL. This
would result in a trap when attach_nobh_buffers() attempted to access
bh->b_this_page.
This can be illustrated by running the writev01 testcase from LTP on jfs.
This error was introduced by commit 5b41e74a "vfs: fix data leak in
nobh_write_end()". That patch did not take into account that if
PageMappedToDisk() is true upon entry to nobh_write_begin(), then no
buffers will be allocated for the page. In that case, we won't have to
worry about a failed write leaving unitialized data in the page.
Of course, head != NULL implies !page_has_buffers(page), so no need to
test both.
Signed-off-by: Dave Kleikamp <shaggy@xxxxxxxxxxxxxxxxxx>
Cc: Bill Pemberton <wfp5p@xxxxxxxxxxxx>
Cc: Dmitri Monakhov <dmonakhov@xxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN fs/buffer.c~vfs-dont-call-attach_nobh_buffers-with-an-empty-list fs/buffer.c
--- a/fs/buffer.c~vfs-dont-call-attach_nobh_buffers-with-an-empty-list
+++ a/fs/buffer.c
@@ -2688,7 +2688,7 @@ int nobh_write_end(struct file *file, st
struct buffer_head *bh;
BUG_ON(fsdata != NULL && page_has_buffers(page));
- if (unlikely(copied < len) && !page_has_buffers(page))
+ if (unlikely(copied < len) && head)
attach_nobh_buffers(page, head);
if (page_has_buffers(page))
return generic_write_end(file, mapping, pos, len,
_
Patches currently in -mm which might be from shaggy@xxxxxxxxxxxxxxxxxx are
origin.patch
linux-next.patch
vfs-dont-call-attach_nobh_buffers-with-an-empty-list.patch
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