Messages in this thread Patch in this message | | | Date | Sun, 13 Apr 2003 03:32:29 -0600 | From | Lou Langholtz <> | Subject | [PATCH] network block device driver, kernel 2.4 |
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Here's a simple patch to nbd.c to fix some of the potential for oopses (and possible corruption) should the nbd-client that handed off a socket exit (implicitly closing the socket), while the driver is still sending requests onto that socket. The oops can easily be seen when root runs "nbd-client -d /dev/nbX" after /dev/nbX has been setup and still has a bunch of I/O buffered up (and is sending requests to the socket to handle the queue). This patch doesn't change functionality.
Louis D. Langholtz --- linux-2.4.20/drivers/block/nbd.c 2002-08-02 18:39:43.000000000 -0600 +++ linux/drivers/block/nbd.c 2003-04-13 02:24:26.000000000 -0600 @@ -26,6 +26,8 @@ * reduce number of partial TCP segments sent. <steve@chygwyn.com> * 01-12-6 Fix deadlock condition by making queue locks independant of * the transmit lock. <steve@chygwyn.com> + * 03-04-12 Fix some possible ways to oops from the nbd-client closing the + * socket it gave us while we're still using that socket. <ldl@aros.net> * * possible FIXME: make set_sock / set_blksize / set_size / do_it one syscall * why not: would need verify_area and friends, would share yet another @@ -153,7 +155,7 @@ int result; struct nbd_request request; unsigned long size = req->nr_sectors << 9; - struct socket *sock = lo->sock; + struct socket *sock; DEBUG("NBD: sending control, "); request.magic = htonl(NBD_REQUEST_MAGIC); @@ -163,6 +165,8 @@ memcpy(request.handle, &req, sizeof(req)); down(&lo->tx_lock); + sock = lo->sock; + if (!sock) goto error_out; /* we got cleared */ result = nbd_xmit(1, sock, (char *) &request, sizeof(request), req->cmd == WRITE ? MSG_MORE : 0); if (result <= 0) @@ -402,7 +406,10 @@ if (!file) return -EINVAL; lo->file = NULL; + /* ensure we're not in critical section of nbd_send_req() */ + down(&lo->tx_lock); lo->sock = NULL; + up(&lo->tx_lock); fput(file); return 0; case NBD_SET_SOCK: | |