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 3821032D0EE for ; Fri, 4 Sep 2026 14:32:45 +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=1788532366; cv=none; b=mIezeuLCn/otnJ/AiFQSvjjnRK9M9mi+R0paVfs8S89pL6mbe/JKuxMMQdk/Gjl4dUV+5Y1Gxd5pUDy5WsSN1tn+HJ96NfvHbEH1ALaI6u3l5djAgnEeb1Ze+FiOVTGnd0wkv/NVBCaZ9+qxXkm2FvfDE+nbZmzWFNah5qA8RYU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788532366; c=relaxed/simple; bh=pkd/2GYnzAyygrYikwMwScncC+vXx9rKsoLqjVMzJKs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YBBGz7erMgzxF+0tAbc54XI7HkDfZo3TB2CZyLCyiSvX7OyaruSPUNTosafyBvWXZU7EkIuB3yh/46d8LvUhcL9SHbXDd1pPlm05kDeC7G5o52HzTU3VJv0KIVj9j8BoFbevsTr6LeuhoH+V+++E0CpSU3cLyIxvKnKiJxag3o4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nAjvqxqS; 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="nAjvqxqS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6260E1F00A3D; Fri, 4 Sep 2026 14:32:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788532364; bh=AxD0MC1Tnc/o1xozej1h2douAmtkx5ZCiy6t62cfpmI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nAjvqxqSIYkfKP3c1XH2Pv6nneMdapNmBrGo2xCwCbVQVvih2t+MeegbeSPG95E33 KCZRUqMMlFV631uhfcu20ir3J4mdpxXhV4YMKTiyYQxxOqzE9fje4hw/qy6d+QpSLB BmLcUNtL0bdQwrJ8G4tuRaiviv3FyiT9DYnohkRwVnsilT2dP40qzxr/PCIKVY+gFu Z+pVNPUlu7goP7FUginrteRnZRZJsv+yNXUyNSPzRx6ja24aESMA/IctKrr1jIZOc5 4HfOuUUn0/5Pu/E4k1E3iSr+q1CmYJDbKVPTVadTh5E0iNDHM+2ANV8/RkKSvNVns1 EVrgAVq3ROdmA== From: Sasha Levin To: stable@vger.kernel.org Cc: Gabriel Prostitis , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.12.y 1/2] USB: gadget: ffs: fix mm lifetime handling Date: Fri, 4 Sep 2026 10:32:41 -0400 Message-ID: <20260904143242.806049-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090332-backlight-leggings-4547@gregkh> References: <2026090332-backlight-leggings-4547@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 ae34a12080edb..c6eadd3433f27 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -860,9 +860,15 @@ static void ffs_user_copy_worker(struct work_struct *work) unsigned long flags; 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); @@ -1252,16 +1258,20 @@ 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; } @@ -1296,14 +1306,17 @@ 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