pktgen: prevent pktgen from using bad tx queue (64c00d81) · Commits · e / devices / android_kernel_teracube_2e

With the new multi-queue transmit code, it is possible to accidentally make pktgen pick a non-existing tx queue simply by using a stale script to drive pktgen. Access to this non-existing tx queue will then trigger a bad memory access and kill the machine. For example, setting "queue_map_max 2" will cause my machine to die when accessing a garbage spinlock in the non-existing tx queue: BUG: spinlock bad magic on CPU#0, kpktgend_0/564 lock: ffff88001ddf6718, .magic: ffffffff, .owner: /-1, .owner_cpu: 0 Pid: 564, comm: kpktgend_0 Not tainted 2.6.27-rc3 #35 Call Trace: [<ffffffff803a1228>] spin_bug+0xa4/0xac [<ffffffff803a1253>] _raw_spin_lock+0x23/0x123 [<ffffffff8055b06f>] _spin_lock_bh+0x17/0x1b [<ffffffff804cb57d>] pktgen_thread_worker+0xa97/0x1002 [<ffffffff8022874d>] ? finish_task_switch+0x38/0x97 [<ffffffff80242077>] ? autoremove_wake_function+0x0/0x36 [<ffffffff80242077>] ? autoremove_wake_function+0x0/0x36 [<ffffffff804caae6>] ? pktgen_thread_worker+0x0/0x1002 [<ffffffff80241a40>] kthread+0x44/0x6d [<ffffffff8020c399>] child_rip+0xa/0x11 [<ffffffff802419fc>] ? kthread+0x0/0x6d [<ffffffff8020c38f>] ? child_rip+0x0/0x11 The attached patch adds some sanity checking to prevent these sorts of configuration errors. Signed-off-by:

Andrew Gallatin <gallatin@myri.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/pktgen.c

+29 −0

Original line number	Diff line number	Diff line
		@@ -1961,6 +1961,8 @@ static int pktgen_setup_dev(struct pktgen_dev pkt_dev, const char ifname)
		*/
		static void pktgen_setup_inject(struct pktgen_dev *pkt_dev)
		{
		int ntxq;

		if (!pkt_dev->odev) {
		printk(KERN_ERR "pktgen: ERROR: pkt_dev->odev == NULL in "
		"setup_inject.\n");
		@@ -1969,6 +1971,33 @@ static void pktgen_setup_inject(struct pktgen_dev *pkt_dev)
		return;
		}

		/* make sure that we don't pick a non-existing transmit queue */
		ntxq = pkt_dev->odev->real_num_tx_queues;
		if (ntxq <= num_online_cpus() && (pkt_dev->flags & F_QUEUE_MAP_CPU)) {
		printk(KERN_WARNING "pktgen: WARNING: QUEUE_MAP_CPU "
		"disabled because CPU count (%d) exceeds number ",
		num_online_cpus());
		printk(KERN_WARNING "pktgen: WARNING: of tx queues "
		"(%d) on %s \n", ntxq, pkt_dev->odev->name);
		pkt_dev->flags &= ~F_QUEUE_MAP_CPU;
		}
		if (ntxq <= pkt_dev->queue_map_min) {
		printk(KERN_WARNING "pktgen: WARNING: Requested "
		"queue_map_min (%d) exceeds number of tx\n",
		pkt_dev->queue_map_min);
		printk(KERN_WARNING "pktgen: WARNING: queues (%d) on "
		"%s, resetting\n", ntxq, pkt_dev->odev->name);
		pkt_dev->queue_map_min = ntxq - 1;
		}
		if (ntxq <= pkt_dev->queue_map_max) {
		printk(KERN_WARNING "pktgen: WARNING: Requested "
		"queue_map_max (%d) exceeds number of tx\n",
		pkt_dev->queue_map_max);
		printk(KERN_WARNING "pktgen: WARNING: queues (%d) on "
		"%s, resetting\n", ntxq, pkt_dev->odev->name);
		pkt_dev->queue_map_max = ntxq - 1;
		}

		/* Default to the interface's mac if not explicitly set. */

		if (is_zero_ether_addr(pkt_dev->src_mac))