From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f43.google.com (mail-pj1-f43.google.com [209.85.216.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A36EF376A0D for ; Wed, 1 Jul 2026 04:31:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782880281; cv=none; b=cNAEFmw3PZPyqhKX7ApPh+w/Xw/AyuBkOdz7Sta7tMXFyJn+kyPxrsPrZdWK/DfM3f1uYjiG7+RffNTqoJrikw0r1eWHG/fSxFJP1xqOAdz9X8COUhCkB920N6P8WhdCEb53Qw74pOewYoYKVc5/v/JrRUpbcktnZhUvj9GrmNM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782880281; c=relaxed/simple; bh=AWKY4cc9CqfC8Hk+fcXwx0sO+5n7MEB7rG8uG7Wszik=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MCPQwFAhSr6shtY8ZPhKnlSPrVnGlBqvU4/+gCMQBbCiB52j6eCzHQ2dmrcZtbb5B8UwJ1qhURP1wkzCU3D3K1uTkRF6cPr1203OpdQK3/rnKJgpeTxelYzaAgzayS4GYBoqzeYYEYohbcyZugbzFDK9tgXwHe388VyQD2DtFUI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=f+yMIgCY; arc=none smtp.client-ip=209.85.216.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="f+yMIgCY" Received: by mail-pj1-f43.google.com with SMTP id 98e67ed59e1d1-37d46e0d246so92178a91.2 for ; Tue, 30 Jun 2026 21:31:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1782880278; x=1783485078; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=fBDjdsdXK93fPolwyRglgWnhTKiV7F2AKwYz1juHAG4=; b=f+yMIgCYuUtTlbjZ9j/dNtWKYQILJ5qbzLb4ZL6lQ63C4YgKzAq2xotDmSH7TUPPlN qHrJkCFGzzfdCbh9dInaQI0txY1/8B6gHczsbHCMIsnMGO+ME4pY4+NqsODlqReg/vTQ 9/Rpp1gZI0Zxu6l3rL5GOrm98PMSUYATGBGWc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782880278; x=1783485078; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=fBDjdsdXK93fPolwyRglgWnhTKiV7F2AKwYz1juHAG4=; b=kZ0hWfCdqrtjUZmfgUZ7SYP0Mw5kRbjjTugTtsSjvrnZtZwFSFiVNwRfM3YXhGVQPX huJNY7EU3p8nuI62/gLW6cOGIK9pvN7nNU0iJl/4EWUFtXs/f3kOrtSeHW71yQriICoj TKd+8TnmBIRa5yKUd7ohjhJfYakc/tKBOALvOmkGczZ+/Wt3lJDNhXrKU+2E1AqFZElZ UStyZmJJiREaj83lxtUxAD7Grq+HcYEYO0CZGJd8fH6Zmp4M4yuZn/FAr8ZBSd4CBi9L +7sJ/q0eP0fxAWhQNYHbYTvxtt3NrPxEYt/stNHRBS/FEKm+IQc+qXyFtYvVgN7jfN9R cK2Q== X-Forwarded-Encrypted: i=1; AHgh+Rr+h6xkdEL7l6Awh+ZAZ5QnIojo+liPZrhw922ScXuKEgsjlkJ11R5p/EeS7zVCjqYaCsYvcXRM/nj7@vger.kernel.org X-Gm-Message-State: AOJu0YwCp6/286qXPZuSF0/vkqjJrTkmI0VCrCJB7Bl8x//FfyqIXv9M Sffh9FI8NRFvMShnk35BwShHTLxS63VT61UdTKooYicNrsLecT7v46Qm6pysTs0n1TeDpZq1vmS Ah3tbVA== X-Gm-Gg: AfdE7cmBS9kRYuVSlY0V3JP3qzWwnFb1j/XF+GNhVBC7Uf4zOIaiOPyt4FD1uhGbnFp mIuaSJHpjN93RkhGFHJjfgppTjh2xEJt7ENCkJ3GdaJDWFnv/L/vNPFlHLOHVZXgan6TSboaYRP Ogsk9/AvmjHIoSclhiFuIXGXLCyapAj1qw5EFs4AnerX0BMRpTqS4aj73rqRY0eJr689Ysjni0x aTIQNNmaOHrynNK+0pihmW9UMIyO9POuPiBX3dbIHK1v9Lc6SgWu24ICegKwVY92vlWS4qfcHoW qgWBNt3f6KuqzFHg4WtS3yXOwc4++ZrTxf7XsRP0Pb/YqqOMJV++Ql0NjpV31zb8nrLEW8+6Nhg VbOjzFcfF5EDxcur+4Xpoujd4GiSfyiFnD7+oRfVspyYmg1b5QWTU4hSTnmmCQODe2rMMND6oIN sYA3n2NtB/as2baW7zYvzxUw5zGTpBkl+6f/4lzZyNlUp/JUaPZfBT X-Received: by 2002:a17:90b:4c07:b0:380:7d9f:81f1 with SMTP id 98e67ed59e1d1-380aa098483mr158214a91.3.1782880277528; Tue, 30 Jun 2026 21:31:17 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:1379:da2f:9be6:bff2]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-38097ba48d0sm360301a91.1.2026.06.30.21.31.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jun 2026 21:31:17 -0700 (PDT) Date: Wed, 1 Jul 2026 13:31:12 +0900 From: Sergey Senozhatsky To: sashiko-reviews@lists.linux.dev Cc: Sergey Senozhatsky , linux-scsi@vger.kernel.org Subject: Re: [RFC PATCH] usb: storage: uas: limit consecutive device resets in error handling Message-ID: References: <20260701040335.810297-1-senozhatsky@chromium.org> <20260701041700.EB7971F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260701041700.EB7971F000E9@smtp.kernel.org> On (26/07/01 04:17), sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: > - [High] Prematurely clearing `devinfo->resetting` and dropping the lock before calling `uas_zap_pending()` creates a race window with `uas_do_work()`, leading to a kernel warning and Use-After-Free. > - [Medium] Time-of-Check to Time-of-Use (TOCTOU) race when reading the `uas_reset_limit` module parameter. [..] > > + spin_lock_irqsave(&devinfo->lock, flags); > > + if (uas_reset_limit > 0 && devinfo->reset_cnt >= uas_reset_limit) { > > [Severity: Medium] > Can a concurrent sysfs write cause a Time-of-Check to Time-of-Use race here? > > The module parameter uas_reset_limit has 0644 permissions. It is read twice > in this condition without a READ_ONCE() wrapper. If it is modified from a > positive value to zero or negative strictly between the two evaluations, the > first check (uas_reset_limit > 0) could pass, while the second check could > evaluate against the new zero or negative value, prematurely failing the reset > and offlining the device. Sounds reasonable. > > > + devinfo->resetting = 0; > > + spin_unlock_irqrestore(&devinfo->lock, flags); > > + uas_zap_pending(devinfo, DID_NO_CONNECT); > > [Severity: High] > Does clearing devinfo->resetting and dropping the lock before calling > uas_zap_pending() introduce a race condition with uas_do_work()? Yes, this looks wrong. Let me take a look.