From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dl1-f44.google.com (mail-dl1-f44.google.com [74.125.82.44]) (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 9FB083C13F0 for ; Wed, 13 May 2026 23:10:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.44 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778713851; cv=none; b=Oxvq2/JaTgSeHmO8LMwHgDjtt5PbBPng94nVMFd8H6vHgu/XCDfFVkf63x9B0B0k9szMhj5nUl7urXn1WpYODOSh0KtNPDep2T6QmL+66vgzbtwZXZ5aJjU35uuSJKo1eXi+IsLGLfnmR5SSPGxG39NenrM9+YeV/pfiebSvOLc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778713851; c=relaxed/simple; bh=W9yeG+3Ka2cA0xHkYcdXnWyiOeXCVFl/QwdWlrW/2F4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=O5pWiipKevdfIJY/jpzkK3YINHbBUXrFbEg32+BUYczTd2wicxx26X53YlAj4TysKXimpXh7M58YZJrC0v9PIs3oFmx4TbPHBc+1Ur84rfYMzCWe1vZvFTE7YOl0Ab3LIYK+rE+ZisFzKPOy+WME2FqCuInFsJx0WR+5tg2YDcw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=JgVg3lJp; arc=none smtp.client-ip=74.125.82.44 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JgVg3lJp" Received: by mail-dl1-f44.google.com with SMTP id a92af1059eb24-1332772f6b3so5839188c88.1 for ; Wed, 13 May 2026 16:10:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1778713850; x=1779318650; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=Qim8OJlV4e6gO+wndPww4vOZ3ay7Pc4+ciEhjYKer88=; b=JgVg3lJpEB3dXwiw2aAmVtOfaoRQ3GhWoPtX/E//rDoyjShf7xfo0Xr4nYTysB44xw j4OfdhuSEkmk2ll80KO0vieLo9NQY6YJHh6bVYyydIGFd3+3Y13r4bREg90zcEhrm83D kiuXDW84Qki5THEkaPypJB5KXR0J2kmyKmu9GfY/Ezj4k1SdJb796f/YbpHPwPXds/6C W8xY7wQtoNcBgFoFrcs9Ksx1cKmdHojCYfj+Q7g8OeynphGTU9sD9CpAFJ0G0hRyC8Dm vRVIHfLSiaT4jyzth08YQ4rKMmJqAIT63qxbnTWJTXnEmAopZXCTks47TJSvTulkybyF ssuQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778713850; x=1779318650; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Qim8OJlV4e6gO+wndPww4vOZ3ay7Pc4+ciEhjYKer88=; b=MFIJ773hf5+FCqq+vvoTfhgWmD9/jCTyf8q0YsHr2QNv3PlNsAWUmnPMFf2u5ep1eo ic4HG0fnkWuIM48ldK7SSpUMiI6o50IVAhptgNch2PKj/aMVfujUT96ynBxuG9Myviox IyNkpOyTbW0OOLiar1ap2D7ebc9b2b9EkmG3jIQj3gYgD8NtZrHVj9Z3CHFiMCM4KflT KKMnTWBema5Fwp0/zkYCmZkI5hQlwJzDIdzGg7sPi8ESEZMEE8/G5TtzpfR8ujkcptSB xUElg8fEeyCfSPiMSg4zjRaAA/jiPu8q5wSrt8EDeHdaycoBZkrXiYeHU0iTmpj30Q8p OqDQ== X-Forwarded-Encrypted: i=1; AFNElJ9S4L1ScRIztJtuK5uha9HrV1tj/6atBqc1XBscEiqychE3Ny+Znw7dOLNmdt1hg7EWwDiymbLggW4=@vger.kernel.org X-Gm-Message-State: AOJu0Yxoy5jDoWmx9zyh+gV06SObbRCsyG4VayCn7+ls9hww/mRpI5rr XG5kq9fQndXnawbZddqH5A9g565f0Xb8Dgklf8l+OQqfj1YwuVwIPVYM X-Gm-Gg: Acq92OFMHytrrElvH2N8dgv/gNlbGI09aX/zHdFvx5VcXybb5EKh3uBBZU7s7jrvU96 FbVeh8ufKdWv8BZBZWn1Bs3GD54SQ4g7qCuzp/jo71zxQxisMaI21t41tLLtRpEV087sATVM3+s n1L3Wi41k9xWRZq6VQfOIXnTLR/w+oY6C9UtlxhVJqsf+KeG6c17lvO33QPTRQQTN/EiiMTtIP/ 4E/k9zTvM17xHk/iAUR54ygC4sEMx5b9Z26hCYnpUHbkArla8a5GH99Qx3X2MsJRR4DXFJ3gtqp xRTfYLhrnur0Ocwc4ik7Yq4RjIeMCbIG6AnGOIzyhtJ9ocVvmqwDWJgwrvxOOLIyTfnGeat1n80 ffRAL4XOGvEZFNYoNDWzQvSpzW8zhdSJfleu4AwViEp04m37+6Jvis+ziDECZuXG35dikCexL6/ H42cB6R7QXHk3P4LHPbH5RDuP/2VOa2kRQh85jiPJq6HwDDt/Rt42PAKUC5VXUGWPjqEH9LcndP w== X-Received: by 2002:a05:7022:b8d:b0:12d:de3f:d84b with SMTP id a92af1059eb24-13436baee2amr3317677c88.36.1778713849690; Wed, 13 May 2026 16:10:49 -0700 (PDT) Received: from gio.tailc60d82.ts.net (209-147-138-114.nat.asu.edu. [209.147.138.114]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30293e2e686sm1046968eec.5.2026.05.13.16.10.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 May 2026 16:10:49 -0700 (PDT) From: Giorgi Kobakhia To: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org Cc: Giorgi Kobakhia Subject: [PATCH usb v4] usb: gadget: f_fs: fix NULL dereference in ffs_dmabuf_detach() Date: Wed, 13 May 2026 16:10:41 -0700 Message-ID: <20260513231041.77176-1-mrkobush@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ffs_dmabuf_detach() dereferences ffs->gadget->dev.parent without checking whether the FunctionFS instance is still bound to UDC. This can be triggered by mounting FunctionFS, binding it to UDC instance. Then unbind would make ffs->gadget = NULL. Calling ffs_epfile_ioctl with code FUNCTIONFS_DMABUF_DETACH ends up in ffs_dmabuf_detach, dereferencing ffs->gadget. Crash Log: Oops: general protection fault KASAN: null-ptr-deref in range [0x00000000000000b0-0x00000000000000b7] RIP: 0010:ffs_epfile_ioctl+0x3f1/0x25d0 Fix this by checking ffs->gadget under ffs->mutex, taking a reference to the parent device before dropping the lock, and returning -ENODEV if the gadget has already been removed. Fixes: 7b07a2a7ca02 ("usb: gadget: functionfs: Add DMABUF import interface") Signed-off-by: Giorgi Kobakhia --- drivers/usb/gadget/function/f_fs.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 002c3441bea3..67c8e65a5aa6 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -1553,14 +1553,27 @@ static int ffs_dmabuf_detach(struct file *file, int fd) { struct ffs_epfile *epfile = file->private_data; struct ffs_data *ffs = epfile->ffs; - struct device *dev = ffs->gadget->dev.parent; + struct device *dev; struct ffs_dmabuf_priv *priv, *tmp; struct dma_buf *dmabuf; int ret = -EPERM; + mutex_lock(&ffs->mutex); + if (!ffs->gadget) { + mutex_unlock(&ffs->mutex); + return -ENODEV; + } + dev = get_device(ffs->gadget->dev.parent); + mutex_unlock(&ffs->mutex); + + if (!dev) + return -ENODEV; + dmabuf = dma_buf_get(fd); - if (IS_ERR(dmabuf)) - return PTR_ERR(dmabuf); + if (IS_ERR(dmabuf)) { + ret = PTR_ERR(dmabuf); + goto out_put_dev; + } mutex_lock(&epfile->dmabufs_mutex); @@ -1585,6 +1598,8 @@ static int ffs_dmabuf_detach(struct file *file, int fd) mutex_unlock(&epfile->dmabufs_mutex); dma_buf_put(dmabuf); +out_put_dev: + put_device(dev); return ret; } -- 2.43.0