From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52088) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gX6MR-0000hE-3l for qemu-devel@nongnu.org; Wed, 12 Dec 2018 10:23:48 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gX6MO-00006n-F1 for qemu-devel@nongnu.org; Wed, 12 Dec 2018 10:23:42 -0500 Received: from mail-wm1-x330.google.com ([2a00:1450:4864:20::330]:37659) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1gX6MK-0008VB-O6 for qemu-devel@nongnu.org; Wed, 12 Dec 2018 10:23:38 -0500 Received: by mail-wm1-x330.google.com with SMTP id g67so6365305wmd.2 for ; Wed, 12 Dec 2018 07:23:35 -0800 (PST) Sender: Paolo Bonzini From: Paolo Bonzini Date: Wed, 12 Dec 2018 16:22:35 +0100 Message-Id: <1544628195-37728-15-git-send-email-pbonzini@redhat.com> In-Reply-To: <1544628195-37728-1-git-send-email-pbonzini@redhat.com> References: <1544628195-37728-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 14/54] block/iscsi: fix ioctl cancel use-after-free List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Stefan Hajnoczi From: Stefan Hajnoczi iscsi_aio_cancel() does not increment the request's reference count, causing a use-after-free when ABORT TASK finishes after the request has already completed. There are some additional issues with iscsi_aio_cancel(): 1. Several ABORT TASKs may be sent for the same task if iscsi_aio_cancel() is invoked multiple times. It's better to avoid this just in case the command identifier is reused. 2. The iscsilun->mutex protection is missing in iscsi_aio_cancel(). Reported-by: Felipe Franciosi Signed-off-by: Stefan Hajnoczi Message-Id: <20180203061621.7033-4-stefanha@redhat.com> Reviewed-by: Felipe Franciosi Tested-by: Sreejith Mohanan Signed-off-by: Paolo Bonzini --- block/iscsi.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/block/iscsi.c b/block/iscsi.c index 1924a2b..abb872d 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -124,6 +124,7 @@ typedef struct IscsiAIOCB { #ifdef __linux__ sg_io_hdr_t *ioh; #endif + bool cancelled; } IscsiAIOCB; /* libiscsi uses time_t so its enough to process events every second */ @@ -287,6 +288,7 @@ static void iscsi_co_init_iscsitask(IscsiLun *iscsilun, struct IscsiTask *iTask) }; } +/* Called (via iscsi_service) with QemuMutex held. */ static void iscsi_abort_task_cb(struct iscsi_context *iscsi, int status, void *command_data, void *private_data) @@ -295,6 +297,7 @@ iscsi_abort_task_cb(struct iscsi_context *iscsi, int status, void *command_data, acb->status = -ECANCELED; iscsi_schedule_bh(acb); + qemu_aio_unref(acb); /* acquired in iscsi_aio_cancel() */ } static void @@ -303,14 +306,25 @@ iscsi_aio_cancel(BlockAIOCB *blockacb) IscsiAIOCB *acb = (IscsiAIOCB *)blockacb; IscsiLun *iscsilun = acb->iscsilun; - if (acb->status != -EINPROGRESS) { + qemu_mutex_lock(&iscsilun->mutex); + + /* If it was cancelled or completed already, our work is done here */ + if (acb->cancelled || acb->status != -EINPROGRESS) { + qemu_mutex_unlock(&iscsilun->mutex); return; } + acb->cancelled = true; + + qemu_aio_ref(acb); /* released in iscsi_abort_task_cb() */ + /* send a task mgmt call to the target to cancel the task on the target */ - iscsi_task_mgmt_abort_task_async(iscsilun->iscsi, acb->task, - iscsi_abort_task_cb, acb); + if (iscsi_task_mgmt_abort_task_async(iscsilun->iscsi, acb->task, + iscsi_abort_task_cb, acb) < 0) { + qemu_aio_unref(acb); /* since iscsi_abort_task_cb() won't be called */ + } + qemu_mutex_unlock(&iscsilun->mutex); } static const AIOCBInfo iscsi_aiocb_info = { @@ -1008,6 +1022,7 @@ static BlockAIOCB *iscsi_aio_ioctl(BlockDriverState *bs, acb->bh = NULL; acb->status = -EINPROGRESS; acb->ioh = buf; + acb->cancelled = false; if (req != SG_IO) { iscsi_ioctl_handle_emulated(acb, req, buf); -- 1.8.3.1