From: Ryusuke Konishi <konishi.ryusuke@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-nilfs@vger.kernel.org,
syzbot <syzbot+53369d11851d8f26735c@syzkaller.appspotmail.com>,
syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: [PATCH] nilfs2: prevent general protection fault in nilfs_clear_dirty_page()
Date: Mon, 12 Jun 2023 11:14:56 +0900 [thread overview]
Message-ID: <20230612021456.3682-1-konishi.ryusuke@gmail.com> (raw)
In-Reply-To: <000000000000da4f6b05eb9bf593@google.com>
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.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+53369d11851d8f26735c@syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/000000000000da4f6b05eb9bf593@google.com
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: stable@vger.kernel.org
---
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 5cf30827f244..b4e54d079b7d 100644
--- a/fs/nilfs2/page.c
+++ b/fs/nilfs2/page.c
@@ -370,7 +370,15 @@ void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
struct folio *folio = fbatch.folios[i];
folio_lock(folio);
- nilfs_clear_dirty_page(&folio->page, silent);
+
+ /*
+ * This folio may have been removed from the address
+ * space by truncation or invalidation when the lock
+ * was acquired. Skip processing in that case.
+ */
+ if (likely(folio->mapping == mapping))
+ nilfs_clear_dirty_page(&folio->page, silent);
+
folio_unlock(folio);
}
folio_batch_release(&fbatch);
--
2.34.1
prev parent reply other threads:[~2023-06-12 2:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <000000000000da4f6b05eb9bf593@google.com>
2023-06-11 3:56 ` [syzbot] [nilfs?] general protection fault in nilfs_clear_dirty_page syzbot
2023-06-11 21:18 ` syzbot
2023-06-12 3:30 ` Christoph Hellwig
2023-06-12 3:59 ` Ryusuke Konishi
2023-06-12 2:14 ` Ryusuke Konishi [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230612021456.3682-1-konishi.ryusuke@gmail.com \
--to=konishi.ryusuke@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nilfs@vger.kernel.org \
--cc=syzbot+53369d11851d8f26735c@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).