From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 D0F24330D35 for ; Fri, 4 Sep 2026 14:29:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788532183; cv=none; b=rA7kUXKS05iytixGlh/19p9q4TFZ+lCQT4W5dA71AyyEVAdHEmwxUoCjcafxZIMkuakTnNdCrvk+fbBYqEQQKjwzITDQzIUFpo1XIQMQDrmY+x1St9uZLgS3MlDj1RfCD3t4aDNGhNyuQN4cy34E/vo/JiooCne4Ue1K9cVo+Z8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788532183; c=relaxed/simple; bh=LKfkAPEsOpFos/BavIJOvjN1BiZ6HKAdnR9T6j8g99Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QgWiOjxVVkiddRe+bpz0/5DEJ8TW7OnS58jcLxb//hWm6UKVtuMz//gNH0V5E8XoZI44EjynYmn1MIqu8u0SV0XHaLvw1d1KzwCq7rhkX290puKz9vWojz36rfdpHy8oBnfEP3MQi3jGnJIBNFIwp6SmYVAzEygBJCrXGPQ1Uzk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gIPZ7dgo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gIPZ7dgo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDB571F00A3D; Fri, 4 Sep 2026 14:29:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788532181; bh=kdvHMwnk3kgNnRM/ORJX2XoyEvSIfqXx7jShtABhuA0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gIPZ7dgoU0ihm29RRyrp4skFfjFy4pLAvQGzuGx7LI8MGmXSQ3qDGCogKnNSbugA4 AXBujEtYrFGKKJfTVbKl1jSRpj8QUSpqM1DjrgznR2Xecd/49WjrCUxTQ2c2J+nX+Y sMLgiXda/bnc3uJjSek0qr9pWR/nGiOof+Xi4uvXLlUnQ4NPaIeGVDFGVX0t72lAdP 9OXaUllh9gDYvEgODJXpfy/bKIl3HiA526jbihGA+TAU02lCtzOlUmn2hA5g27mCB1 Tns8Tgpk2khlN9FWPA38gtFkd0Og7+m27PImpZPJorQs7k6gn7lSZPDhIV/U/2b5Gw vTvWtxVCLYg5Q== From: Sasha Levin To: stable@vger.kernel.org Cc: Gabriel Prostitis , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.18.y 1/2] USB: gadget: ffs: fix mm lifetime handling Date: Fri, 4 Sep 2026 10:29:38 -0400 Message-ID: <20260904142939.798242-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090331-width-covenant-cd4e@gregkh> References: <2026090331-width-covenant-cd4e@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Gabriel Prostitis [ Upstream commit 5eb5c72c72fef76cb765ef1669b62b6a3ba1bfc8 ] io_data stores a pointer to the submitting task's mm_struct, but does not currently hold a reference to it while async requests are pending. This can result in a use-after-free if the task exits before completion handling finishes. Take a reference with mmgrab() when queuing the read request and release it with mmdrop() on request completion. Reported-by: Gabriel Prostitis Signed-off-by: Gabriel Prostitis Link: https://patch.msgid.link/20260601-mm-uaf-fix-v2-1-3c942a707bce@gmail.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: e78dcb1f7ec2 ("usb: gadget: f_fs: Fix Use-After-Free in AIO error path") Signed-off-by: Sasha Levin --- drivers/usb/gadget/function/f_fs.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 3116060977185..a00bf66bdf878 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -857,9 +857,15 @@ static void ffs_user_copy_worker(struct work_struct *work) bool kiocb_has_eventfd = io_data->kiocb->ki_flags & IOCB_EVENTFD; if (io_data->read && ret > 0) { - kthread_use_mm(io_data->mm); - ret = ffs_copy_to_iter(io_data->buf, ret, &io_data->data); - kthread_unuse_mm(io_data->mm); + if (mmget_not_zero(io_data->mm)) { + kthread_use_mm(io_data->mm); + ret = ffs_copy_to_iter(io_data->buf, ret, &io_data->data); + kthread_unuse_mm(io_data->mm); + mmput(io_data->mm); + } else { + ret = -EFAULT; + } + mmdrop(io_data->mm); } io_data->kiocb->ki_complete(io_data->kiocb, ret); @@ -1240,16 +1246,20 @@ static ssize_t ffs_epfile_write_iter(struct kiocb *kiocb, struct iov_iter *from) kiocb->private = p; - if (p->aio) + if (p->aio) { + mmgrab(p->mm); kiocb_set_cancel_fn(kiocb, ffs_aio_cancel); + } res = ffs_epfile_io(kiocb->ki_filp, p); if (res == -EIOCBQUEUED) return res; - if (p->aio) + if (p->aio) { + mmdrop(p->mm); kfree(p); - else + } else { *from = p->data; + } return res; } @@ -1284,14 +1294,17 @@ static ssize_t ffs_epfile_read_iter(struct kiocb *kiocb, struct iov_iter *to) kiocb->private = p; - if (p->aio) + if (p->aio) { + mmgrab(p->mm); kiocb_set_cancel_fn(kiocb, ffs_aio_cancel); + } res = ffs_epfile_io(kiocb->ki_filp, p); if (res == -EIOCBQUEUED) return res; if (p->aio) { + mmdrop(p->mm); kfree(p->to_free); kfree(p); } else { -- 2.53.0