From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f198.google.com (mail-oi1-f198.google.com [209.85.167.198]) (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 27D81483BFA for ; Fri, 24 Jul 2026 23:51:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784937069; cv=none; b=KZtMmkAwVA80YBedWznXXDb9UrhMqOyaglA15bbgmjn6RA8CeqUGRZEUTEu2/nMeQGOy4w7X0jmL831UzOlv95PpuupE1D+c7B9zpeEJEemimJ3nY/TqwnH8Y/Hp64D6F4EBoWMdmJK91XxuzhZYvnjxpsP46P2ydxgqgiwEXwQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784937069; c=relaxed/simple; bh=jlsa4KOozpF8lkrLjI7QECxAXU6Mr2HPk7AjzRmvTT0=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=hICsmm8/CSOzesjFjzEWqtU6bvzDNyCfNNJXm/Po+pMPEaVE+I/AmVsDVwvEnrOSoX0oHbFK0kh4j5/Qln4qaon7klPFzzJkk9Yfi7sSWdeXciE5AHxjXDTRRuGTJ9T/3M1HtQYqRatn3yNRlZPa9IwwTQy/M6qYZuVfDxs7QTY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--nkapron.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=KrWKA/l/; arc=none smtp.client-ip=209.85.167.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--nkapron.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="KrWKA/l/" Received: by mail-oi1-f198.google.com with SMTP id 5614622812f47-495b0cf250dso560630b6e.3 for ; Fri, 24 Jul 2026 16:51:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1784937065; x=1785541865; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:mime-version:date:from :to:cc:subject:date:message-id:reply-to:content-type; bh=inDwNhTjfAEReKAs3ZD3SpJEd1qaXM6z94+m+5MyCOI=; b=KrWKA/l/K3yEmPVhNxPShdtdmnW2KhIyx5L5cnbi6UqpAyMIKZlGDb+Ij+Ux1h+QtY lw/5mqB+bfEzMDok2cpBHdNWC5aWHc2P85hMCD6gCoafp1wFCThuVqr9+wNk5pd4gOoU rvwj1rmaMtWxfYK94uM9JFRlXstpybvu1bAddjMbOAQeNKkPiTSXie6YwWrqCZgtboj9 7oIAWYiwpF6gyoWta1hwNdsFyDVJeRSztGfnKWLnViSYnotvJOiaUrtZ8mMFCuARTSJw GYaEoaPp5zl/x3ngNtMqaIbYO1mnYoJYesEbwbFjUcfQRo549sST0b7zRYc58n7+d5N7 LxsQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784937065; x=1785541865; h=content-type:cc:to:from:subject:message-id:mime-version:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=inDwNhTjfAEReKAs3ZD3SpJEd1qaXM6z94+m+5MyCOI=; b=qbh4WZFWD/a4hqMO5QNidABtsXzgv6XVralealCgirJoQRS2IqVImM3WbjP5GH5GN/ +CemrJOnJ9qM61UBo21HT27J0fvQOHqhV3JpY+EO8FV44Ag4zVBMam78sN2hEMAP/QIH 8i6YcuUgol/44ZeTPzZNyrb1wbgI9qbgYWt+bSeE97xoXE6xm7Ef4QWwJ1nzseAaePeI Stsb6XE30VJgug0MmlGebEARoN0F6UFPzDyixwUPMR8l3xrTkZ1GNuSY6fAojFhXFYFo ZHzj6gW7B3Y7dINzqd5bQ9StbscLQHdG8xr90GUjcBlFhgRvuhD2QRK4qNeIQMUxtQWy XfHA== X-Forwarded-Encrypted: i=1; AHgh+RpdjjnuMlIwBLDvfXJ/lrRm5vp1kBRf1fjitEmLKy4Sw0SFKlG+g8zRSlQinbUYv1AxqVbeCv26XBsjdRE=@vger.kernel.org X-Gm-Message-State: AOJu0YxboF2zFTgODSWsNtTyJl6aYOh9JcDfFVh4CqWXwqmZO1DYZDkI UibQ1KrwAKfu8kwdSUjay6m9d4+aAiCb0YzbYPJWcs6IGxbq5sbwg9XOKJO6P6ot/BKvodHIHhc jqs/Lh0f2Xg== X-Received: from ilnz9.prod.google.com ([2002:a92:cd09:0:b0:505:f2f1:cf8f]) (user=nkapron job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6808:23c2:b0:4a4:a693:9d87 with SMTP id 5614622812f47-4ab69f5951fmr680108b6e.5.1784937065410; Fri, 24 Jul 2026 16:51:05 -0700 (PDT) Date: Fri, 24 Jul 2026 23:51:00 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.229.g6434b31f56-goog Message-ID: <20260724235100.106011-1-nkapron@google.com> Subject: [PATCH] usb: gadget: f_fs: Fix Use-After-Free in AIO error path From: Neill Kapron To: Greg Kroah-Hartman , Al Viro Cc: nkapron@google.com, kernel-team@android.com, stable@vger.kernel.org, Xingyu Jin , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" In ffs_epfile_write_iter() and ffs_epfile_read_iter(), when ffs_epfile_io() fails with an error other than -EIOCBQUEUED, the io_data structure (`p`) is freed. However, for AIO operations, the kiocb cancel function was already armed and kiocb->private was set to `p`. If a concurrent cancel operation (such as sys_io_cancel()) executes after ffs_epfile_io() fails but before the function frees `p`, a Use-After-Free can occur when the cancellation handler accesses the freed pointer. To securely fix this race condition, we must properly un-arm the cancellation. Invoking `kiocb->ki_complete()` does exactly this by acquiring `ctx->ctx_lock` and safely removing the kiocb from the active sequence. In doing so, it ensures that a parallel io_cancel can no longer discover the kiocb, effectively closing the race window. We then return -EIOCBQUEUED to notify the VFS layer that the kiocb has been consumed and it should avoid attempting to complete the request again or triggering subsequent completion handlers. Fixes: de2080d41b5d ("gadget/function/f_fs.c: close leaks") Cc: stable@vger.kernel.org Reported-by: Xingyu Jin Assisted-by: Antigravity:gemini-3.1-pro Signed-off-by: Neill Kapron --- drivers/usb/gadget/function/f_fs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 073c4cbd90fb..8e9bf0bdbcdb 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -1290,8 +1290,10 @@ static ssize_t ffs_epfile_write_iter(struct kiocb *kiocb, struct iov_iter *from) if (res == -EIOCBQUEUED) return res; if (p->aio) { + kiocb->ki_complete(kiocb, res); mmdrop(p->mm); kfree(p); + return -EIOCBQUEUED; } else { *from = p->data; } @@ -1339,9 +1341,11 @@ static ssize_t ffs_epfile_read_iter(struct kiocb *kiocb, struct iov_iter *to) return res; if (p->aio) { + kiocb->ki_complete(kiocb, res); mmdrop(p->mm); kfree(p->to_free); kfree(p); + return -EIOCBQUEUED; } else { *to = p->data; } -- 2.55.0.229.g6434b31f56-goog