From cbfee3d9d5c0f7c35f3314667339abe2410b2d90 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Mon, 12 Jun 2023 11:14:56 +0900 Subject: [PATCH] nilfs2: prevent general protection fault in nilfs_clear_dirty_page() commit 782e53d0c14420858dbf0f8f797973c150d3b6d7 upstream. In a syzbot stress test that deliberately causes file system errors on nilfs2 with a corrupted disk image, it has been reported that nilfs_clear_dirty_page() called from nilfs_clear_dirty_pages() can cause a general protection fault. In nilfs_clear_dirty_pages(), when looking up dirty pages from the page cache and calling nilfs_clear_dirty_page() for each dirty page/folio retrieved, the back reference from the argument page to "mapping" may have been changed to NULL (and possibly others). It is necessary to check this after locking the page/folio. So, fix this issue by not calling nilfs_clear_dirty_page() on a page/folio after locking it in nilfs_clear_dirty_pages() if the back reference "mapping" from the page/folio is different from the "mapping" that held the page/folio just before. Link: https://lkml.kernel.org/r/20230612021456.3682-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi Reported-by: syzbot+53369d11851d8f26735c@syzkaller.appspotmail.com Closes: https://lkml.kernel.org/r/000000000000da4f6b05eb9bf593@google.com Tested-by: Ryusuke Konishi Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- fs/nilfs2/page.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c index 39b7eea2..7d31833 100644 --- a/fs/nilfs2/page.c +++ b/fs/nilfs2/page.c @@ -369,7 +369,15 @@ void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent) struct page *page = pvec.pages[i]; lock_page(page); - nilfs_clear_dirty_page(page, silent); + + /* + * This page may have been removed from the address + * space by truncation or invalidation when the lock + * was acquired. Skip processing in that case. + */ + if (likely(page->mapping == mapping)) + nilfs_clear_dirty_page(page, silent); + unlock_page(page); } pagevec_release(&pvec); -- 2.7.4