From bd8a89debc48bb6696c58a346b463d8df18febb2 Mon Sep 17 00:00:00 2001 From: Daniel Willmann Date: Tue, 10 Jun 2014 10:02:24 +0200 Subject: write_queue: Avoid possible use-after-free if fd is read-/writable If the FD is both readable and writable and the read callback closes the connection (and frees the surrounding structure) we shouldn't call the write callback (or check anything else in the read fd). With this patch callback functions can return -EBADFD if they don't want the FD to be handled any more. --- src/write_queue.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) (limited to 'src/write_queue.c') diff --git a/src/write_queue.c b/src/write_queue.c index cef40f83..80e6c42e 100644 --- a/src/write_queue.c +++ b/src/write_queue.c @@ -21,6 +21,7 @@ * */ +#include #include /*! \addtogroup write_queue @@ -39,14 +40,21 @@ int osmo_wqueue_bfd_cb(struct osmo_fd *fd, unsigned int what) { struct osmo_wqueue *queue; + int rc; queue = container_of(fd, struct osmo_wqueue, bfd); - if (what & BSC_FD_READ) - queue->read_cb(fd); + if (what & BSC_FD_READ) { + rc = queue->read_cb(fd); + if (rc == -EBADFD) + goto err_badfd; + } - if (what & BSC_FD_EXCEPT) - queue->except_cb(fd); + if (what & BSC_FD_EXCEPT) { + rc = queue->except_cb(fd); + if (rc == -EBADFD) + goto err_badfd; + } if (what & BSC_FD_WRITE) { struct msgb *msg; @@ -58,14 +66,19 @@ int osmo_wqueue_bfd_cb(struct osmo_fd *fd, unsigned int what) --queue->current_length; msg = msgb_dequeue(&queue->msg_queue); - queue->write_cb(fd, msg); + rc = queue->write_cb(fd, msg); msgb_free(msg); + if (rc == -EBADFD) + goto err_badfd; + if (!llist_empty(&queue->msg_queue)) fd->when |= BSC_FD_WRITE; } } +err_badfd: + /* Return value is not checked in osmo_select_main() */ return 0; } -- cgit v1.2.3