From 281e20323ab72180137824a298ee9e21e6f9acf6 Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Sun, 24 Jan 2010 16:45:03 +0100 Subject: [PATCH] firewire: core: fix use-after-free regression in FCP handler Commit db5d247a "firewire: fix use of multiple AV/C devices, allow multiple FCP listeners" introduced a regression into 2.6.33-rc3: The core freed payloads of incoming requests to FCP_Request or FCP_Response before a userspace driver accessed them. We need to copy such payloads for each registered userspace client and free the copies according to the lifetime rules of non-FCP client request resources. (This could possibly be optimized by reference counts instead of copies.) The presently only kernelspace driver which listens for FCP requests, firedtv, was not affected because it already copies FCP frames into an own buffer before returning to firewire-core's FCP handler dispatcher. Signed-off-by: Stefan Richter --- drivers/firewire/core-cdev.c | 50 ++++++++++++++++++++++++++---------- 1 file changed, 36 insertions(+), 14 deletions(-) diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c index e6d63849e78e..4eeaed57e219 100644 --- a/drivers/firewire/core-cdev.c +++ b/drivers/firewire/core-cdev.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include #include @@ -595,13 +596,20 @@ static int ioctl_send_request(struct client *client, void *buffer) client->device->max_speed); } +static inline bool is_fcp_request(struct fw_request *request) +{ + return request == NULL; +} + static void release_request(struct client *client, struct client_resource *resource) { struct inbound_transaction_resource *r = container_of(resource, struct inbound_transaction_resource, resource); - if (r->request) + if (is_fcp_request(r->request)) + kfree(r->data); + else fw_send_response(client->device->card, r->request, RCODE_CONFLICT_ERROR); kfree(r); @@ -616,6 +624,7 @@ static void handle_request(struct fw_card *card, struct fw_request *request, struct address_handler_resource *handler = callback_data; struct inbound_transaction_resource *r; struct inbound_transaction_event *e; + void *fcp_frame = NULL; int ret; r = kmalloc(sizeof(*r), GFP_ATOMIC); @@ -627,6 +636,18 @@ static void handle_request(struct fw_card *card, struct fw_request *request, r->data = payload; r->length = length; + if (is_fcp_request(request)) { + /* + * FIXME: Let core-transaction.c manage a + * single reference-counted copy? + */ + fcp_frame = kmemdup(payload, length, GFP_ATOMIC); + if (fcp_frame == NULL) + goto failed; + + r->data = fcp_frame; + } + r->resource.release = release_request; ret = add_client_resource(handler->client, &r->resource, GFP_ATOMIC); if (ret < 0) @@ -640,13 +661,15 @@ static void handle_request(struct fw_card *card, struct fw_request *request, e->request.closure = handler->closure; queue_event(handler->client, &e->event, - &e->request, sizeof(e->request), payload, length); + &e->request, sizeof(e->request), r->data, length); return; failed: kfree(r); kfree(e); - if (request) + kfree(fcp_frame); + + if (!is_fcp_request(request)) fw_send_response(card, request, RCODE_CONFLICT_ERROR); } @@ -717,18 +740,17 @@ static int ioctl_send_response(struct client *client, void *buffer) r = container_of(resource, struct inbound_transaction_resource, resource); - if (r->request) { - if (request->length < r->length) - r->length = request->length; - if (copy_from_user(r->data, u64_to_uptr(request->data), - r->length)) { - ret = -EFAULT; - kfree(r->request); - goto out; - } - fw_send_response(client->device->card, r->request, - request->rcode); + if (is_fcp_request(r->request)) + goto out; + + if (request->length < r->length) + r->length = request->length; + if (copy_from_user(r->data, u64_to_uptr(request->data), r->length)) { + ret = -EFAULT; + kfree(r->request); + goto out; } + fw_send_response(client->device->card, r->request, request->rcode); out: kfree(r); -- 2.20.1