From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relayaws-01.paragon-software.com (relayaws-01.paragon-software.com [35.157.23.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0D0C922F74A for ; Fri, 16 Jan 2026 13:46:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=35.157.23.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768571180; cv=none; b=lONq+tYqfs5HzkAhmxMl3/pjPR1ZYnhmtOkcwdTUygyGDEGqBx2/gW0JSmBS3cuVFd/sFQvLhNnWyey+j99d90GWGCJ0lyjc/MSUc9nkHKiTr+pRIEJC9LS9XD7D1j7FCtcBE/M+cBZmqcIWzaZDIkNgJ1yjXGFwp7F8WWR10To= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768571180; c=relaxed/simple; bh=1yZMZFYr6KbXJmK//WAV7JgwpTNWTtHywzR2W7BQjLk=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=iHRcA4CbFWL9Mb5zIiRv41ID5PBmFnwJNLBwdAC+vcWuVDpKkLgLjWAuJEci/E5pPt87zXHfSpcO4ji8JivoFXg1Ep+jBHAGPYkI9Sqi93Xd8yGTgsiJ1q5Dd+LoEsIF5Hg+meyZlG9xad+wqy/JsdaJoQlt+9TXekHhY5o7dsI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=paragon-software.com; spf=pass smtp.mailfrom=paragon-software.com; dkim=pass (1024-bit key) header.d=paragon-software.com header.i=@paragon-software.com header.b=L9z5oTiy; arc=none smtp.client-ip=35.157.23.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=paragon-software.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=paragon-software.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=paragon-software.com header.i=@paragon-software.com header.b="L9z5oTiy" Received: from relayfre-01.paragon-software.com (unknown [176.12.100.13]) by relayaws-01.paragon-software.com (Postfix) with ESMTPS id 9425D1D77; Fri, 16 Jan 2026 13:38:15 +0000 (UTC) Authentication-Results: relayaws-01.paragon-software.com; dkim=pass (1024-bit key; unprotected) header.d=paragon-software.com header.i=@paragon-software.com header.b=L9z5oTiy; dkim-atps=neutral Received: from dlg2.mail.paragon-software.com (vdlg-exch-02.paragon-software.com [172.30.1.105]) by relayfre-01.paragon-software.com (Postfix) with ESMTPS id DDED6219B; Fri, 16 Jan 2026 13:40:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paragon-software.com; s=mail; t=1768570853; bh=YXDXoJMMgtVuEp5U1e0l4NdrP69t8fuRn9yRvxghLds=; h=Date:Subject:To:CC:References:From:In-Reply-To; b=L9z5oTiyblfTBx0387Kw2rTyRs3yuh15lq+C8Qc6FFV4Le/tUOfKVYREufZZYCkJT 6szg39vwS1Jb8baGpWWaY8H1ctFxD/K0U25y36WyM4JAR2yow+LyTGV0W+ObxAmf8M sY9zGiWTNkjWQGcMOoKO5hwVnYRCOnw3D8cGUkQU= Received: from [192.168.95.128] (172.30.20.155) by vdlg-exch-02.paragon-software.com (172.30.1.105) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.7; Fri, 16 Jan 2026 16:40:52 +0300 Message-ID: <032f7f9d-d92d-4b11-aa18-21eb62a4d2ab@paragon-software.com> Date: Fri, 16 Jan 2026 14:40:51 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] ntfs3: fix circular locking dependency in run_unpack_ex To: Szymon Wilczek CC: , , References: <20251227144307.8966-1-swilczek.lx@gmail.com> Content-Language: en-US From: Konstantin Komarov In-Reply-To: <20251227144307.8966-1-swilczek.lx@gmail.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: vdlg-exch-02.paragon-software.com (172.30.1.105) To vdlg-exch-02.paragon-software.com (172.30.1.105) On 12/27/25 15:43, Szymon Wilczek wrote: > Syzbot reported a circular locking dependency between wnd->rw_lock > (sbi->used.bitmap) and ni->file.run_lock. > > The deadlock scenario: > 1. ntfs_extend_mft() takes ni->file.run_lock then wnd->rw_lock. > 2. run_unpack_ex() takes wnd->rw_lock then tries to acquire > ni->file.run_lock inside ntfs_refresh_zone(). > > This creates an AB-BA deadlock. > > Fix this by using down_read_trylock() instead of down_read() when > acquiring run_lock in run_unpack_ex(). If the lock is contended, > skip ntfs_refresh_zone() - the MFT zone will be refreshed on the > next MFT operation. This breaks the circular dependency since we > never block waiting for run_lock while holding wnd->rw_lock. > > Reported-by: syzbot+d27edf9f96ae85939222@syzkaller.appspotmail.com > Tested-by: syzbot+d27edf9f96ae85939222@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=d27edf9f96ae85939222 > Signed-off-by: Szymon Wilczek > --- > fs/ntfs3/run.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/fs/ntfs3/run.c b/fs/ntfs3/run.c > index 395b20492525..dc59cad4fa37 100644 > --- a/fs/ntfs3/run.c > +++ b/fs/ntfs3/run.c > @@ -1131,11 +1131,14 @@ int run_unpack_ex(struct runs_tree *run, struct ntfs_sb_info *sbi, CLST ino, > struct rw_semaphore *lock = > is_mounted(sbi) ? &sbi->mft.ni->file.run_lock : > NULL; > - if (lock) > - down_read(lock); > - ntfs_refresh_zone(sbi); > - if (lock) > - up_read(lock); > + if (lock) { > + if (down_read_trylock(lock)) { > + ntfs_refresh_zone(sbi); > + up_read(lock); > + } > + } else { > + ntfs_refresh_zone(sbi); > + } > } > up_write(&wnd->rw_lock); > if (err) Thanks for the patch. It is applied. Regards, Konstantin