From 87b60cfacf9f17cf71933c6e33b66e68160af71d Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 10 Feb 2017 10:31:49 -0800 Subject: net_sched: fix error recovery at qdisc creation Dmitry reported uses after free in qdisc code [1] The problem here is that ops->init() can return an error. qdisc_create_dflt() then call ops->destroy(), while qdisc_create() does _not_ call it. Four qdisc chose to call their own ops->destroy(), assuming their caller would not. This patch makes sure qdisc_create() calls ops->destroy() and fixes the four qdisc to avoid double free. [1] BUG: KASAN: use-after-free in mq_destroy+0x242/0x290 net/sched/sch_mq.c:33 at addr ffff8801d415d440 Read of size 8 by task syz-executor2/5030 CPU: 0 PID: 5030 Comm: syz-executor2 Not tainted 4.3.5-smp-DEV #119 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000046 ffff8801b435b870 ffffffff81bbbed4 ffff8801db000400 ffff8801d415d440 ffff8801d415dc40 ffff8801c4988510 ffff8801b435b898 ffffffff816682b1 ffff8801b435b928 ffff8801d415d440 ffff8801c49880c0 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0x6c/0x98 lib/dump_stack.c:51 [] kasan_object_err+0x21/0x70 mm/kasan/report.c:158 [] print_address_description mm/kasan/report.c:196 [inline] [] kasan_report_error+0x1b4/0x4b0 mm/kasan/report.c:285 [] kasan_report mm/kasan/report.c:305 [inline] [] __asan_report_load8_noabort+0x43/0x50 mm/kasan/report.c:326 [] mq_destroy+0x242/0x290 net/sched/sch_mq.c:33 [] qdisc_destroy+0x12d/0x290 net/sched/sch_generic.c:953 [] qdisc_create_dflt+0xf0/0x120 net/sched/sch_generic.c:848 [] attach_default_qdiscs net/sched/sch_generic.c:1029 [inline] [] dev_activate+0x6ad/0x880 net/sched/sch_generic.c:1064 [] __dev_open+0x221/0x320 net/core/dev.c:1403 [] __dev_change_flags+0x15e/0x3e0 net/core/dev.c:6858 [] dev_change_flags+0x8e/0x140 net/core/dev.c:6926 [] dev_ifsioc+0x446/0x890 net/core/dev_ioctl.c:260 [] dev_ioctl+0x1ba/0xb80 net/core/dev_ioctl.c:546 [] sock_do_ioctl+0x99/0xb0 net/socket.c:879 [] sock_ioctl+0x2a0/0x390 net/socket.c:958 [] vfs_ioctl fs/ioctl.c:44 [inline] [] do_vfs_ioctl+0x8a8/0xe50 fs/ioctl.c:611 [] SYSC_ioctl fs/ioctl.c:626 [inline] [] SyS_ioctl+0x94/0xc0 fs/ioctl.c:617 [] entry_SYSCALL_64_fastpath+0x12/0x17 Signed-off-by: Eric Dumazet Reported-by: Dmitry Vyukov Signed-off-by: David S. Miller --- net/sched/sch_mq.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) (limited to 'net/sched/sch_mq.c') diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c index 2bc8d7f8df16..20b7f1646f69 100644 --- a/net/sched/sch_mq.c +++ b/net/sched/sch_mq.c @@ -52,7 +52,7 @@ static int mq_init(struct Qdisc *sch, struct nlattr *opt) /* pre-allocate qdiscs, attachment can't fail */ priv->qdiscs = kcalloc(dev->num_tx_queues, sizeof(priv->qdiscs[0]), GFP_KERNEL); - if (priv->qdiscs == NULL) + if (!priv->qdiscs) return -ENOMEM; for (ntx = 0; ntx < dev->num_tx_queues; ntx++) { @@ -60,18 +60,14 @@ static int mq_init(struct Qdisc *sch, struct nlattr *opt) qdisc = qdisc_create_dflt(dev_queue, get_default_qdisc_ops(dev, ntx), TC_H_MAKE(TC_H_MAJ(sch->handle), TC_H_MIN(ntx + 1))); - if (qdisc == NULL) - goto err; + if (!qdisc) + return -ENOMEM; priv->qdiscs[ntx] = qdisc; qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT; } sch->flags |= TCQ_F_MQROOT; return 0; - -err: - mq_destroy(sch); - return -ENOMEM; } static void mq_attach(struct Qdisc *sch) -- cgit v1.2.3