[PATCH 4.9 02/72] net_sched: fix error recovery at qdisc creation

From: Greg Kroah-Hartman
Date: Wed Jul 19 2017 - 06:42:35 EST

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4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@xxxxxxxxxx>

commit 87b60cfacf9f17cf71933c6e33b66e68160af71d upstream.

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:
[<ffffffff81bbbed4>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81bbbed4>] dump_stack+0x6c/0x98 lib/dump_stack.c:51
[<ffffffff816682b1>] kasan_object_err+0x21/0x70 mm/kasan/report.c:158
[<ffffffff81668524>] print_address_description mm/kasan/report.c:196 [inline]
[<ffffffff81668524>] kasan_report_error+0x1b4/0x4b0 mm/kasan/report.c:285
[<ffffffff81668953>] kasan_report mm/kasan/report.c:305 [inline]
[<ffffffff81668953>] __asan_report_load8_noabort+0x43/0x50 mm/kasan/report.c:326
[<ffffffff82527b02>] mq_destroy+0x242/0x290 net/sched/sch_mq.c:33
[<ffffffff82524bdd>] qdisc_destroy+0x12d/0x290 net/sched/sch_generic.c:953
[<ffffffff82524e30>] qdisc_create_dflt+0xf0/0x120 net/sched/sch_generic.c:848
[<ffffffff8252550d>] attach_default_qdiscs net/sched/sch_generic.c:1029 [inline]
[<ffffffff8252550d>] dev_activate+0x6ad/0x880 net/sched/sch_generic.c:1064
[<ffffffff824b1db1>] __dev_open+0x221/0x320 net/core/dev.c:1403
[<ffffffff824b24ce>] __dev_change_flags+0x15e/0x3e0 net/core/dev.c:6858
[<ffffffff824b27de>] dev_change_flags+0x8e/0x140 net/core/dev.c:6926
[<ffffffff824f5bf6>] dev_ifsioc+0x446/0x890 net/core/dev_ioctl.c:260
[<ffffffff824f61fa>] dev_ioctl+0x1ba/0xb80 net/core/dev_ioctl.c:546
[<ffffffff82430509>] sock_do_ioctl+0x99/0xb0 net/socket.c:879
[<ffffffff82430d30>] sock_ioctl+0x2a0/0x390 net/socket.c:958
[<ffffffff816f3b68>] vfs_ioctl fs/ioctl.c:44 [inline]
[<ffffffff816f3b68>] do_vfs_ioctl+0x8a8/0xe50 fs/ioctl.c:611
[<ffffffff816f41a4>] SYSC_ioctl fs/ioctl.c:626 [inline]
[<ffffffff816f41a4>] SyS_ioctl+0x94/0xc0 fs/ioctl.c:617
[<ffffffff8123e357>] entry_SYSCALL_64_fastpath+0x12/0x17

Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/sched/sch_api.c | 2 ++
net/sched/sch_hhf.c | 8 ++++++--
net/sched/sch_mq.c | 10 +++-------
net/sched/sch_mqprio.c | 19 ++++++-------------
net/sched/sch_sfq.c | 3 ++-
5 files changed, 19 insertions(+), 23 deletions(-)

--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1008,6 +1008,8 @@ static struct Qdisc *qdisc_create(struct

return sch;
}
+ /* ops->init() failed, we call ->destroy() like qdisc_create_dflt() */
+ ops->destroy(sch);
err_out3:
dev_put(dev);
kfree((char *) sch - sch->padded);
--- a/net/sched/sch_hhf.c
+++ b/net/sched/sch_hhf.c
@@ -627,7 +627,9 @@ static int hhf_init(struct Qdisc *sch, s
q->hhf_arrays[i] = hhf_zalloc(HHF_ARRAYS_LEN *
sizeof(u32));
if (!q->hhf_arrays[i]) {
- hhf_destroy(sch);
+ /* Note: hhf_destroy() will be called
+ * by our caller.
+ */
return -ENOMEM;
}
}
@@ -638,7 +640,9 @@ static int hhf_init(struct Qdisc *sch, s
q->hhf_valid_bits[i] = hhf_zalloc(HHF_ARRAYS_LEN /
BITS_PER_BYTE);
if (!q->hhf_valid_bits[i]) {
- hhf_destroy(sch);
+ /* Note: hhf_destroy() will be called
+ * by our caller.
+ */
return -ENOMEM;
}
}
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -52,7 +52,7 @@ static int mq_init(struct Qdisc *sch, st
/* 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, st
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)
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -118,10 +118,8 @@ static int mqprio_init(struct Qdisc *sch
/* pre-allocate qdisc, attachment can't fail */
priv->qdiscs = kcalloc(dev->num_tx_queues, sizeof(priv->qdiscs[0]),
GFP_KERNEL);
- if (priv->qdiscs == NULL) {
- err = -ENOMEM;
- goto err;
- }
+ if (!priv->qdiscs)
+ return -ENOMEM;

for (i = 0; i < dev->num_tx_queues; i++) {
dev_queue = netdev_get_tx_queue(dev, i);
@@ -129,10 +127,9 @@ static int mqprio_init(struct Qdisc *sch
get_default_qdisc_ops(dev, i),
TC_H_MAKE(TC_H_MAJ(sch->handle),
TC_H_MIN(i + 1)));
- if (qdisc == NULL) {
- err = -ENOMEM;
- goto err;
- }
+ if (!qdisc)
+ return -ENOMEM;
+
priv->qdiscs[i] = qdisc;
qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
}
@@ -148,7 +145,7 @@ static int mqprio_init(struct Qdisc *sch
priv->hw_owned = 1;
err = dev->netdev_ops->ndo_setup_tc(dev, sch->handle, 0, &tc);
if (err)
- goto err;
+ return err;
} else {
netdev_set_num_tc(dev, qopt->num_tc);
for (i = 0; i < qopt->num_tc; i++)
@@ -162,10 +159,6 @@ static int mqprio_init(struct Qdisc *sch

sch->flags |= TCQ_F_MQROOT;
return 0;
-
-err:
- mqprio_destroy(sch);
- return err;
}

static void mqprio_attach(struct Qdisc *sch)
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -742,9 +742,10 @@ static int sfq_init(struct Qdisc *sch, s
q->ht = sfq_alloc(sizeof(q->ht[0]) * q->divisor);
q->slots = sfq_alloc(sizeof(q->slots[0]) * q->maxflows);
if (!q->ht || !q->slots) {
- sfq_destroy(sch);
+ /* Note: sfq_destroy() will be called by our caller */
return -ENOMEM;
}
+
for (i = 0; i < q->divisor; i++)
q->ht[i] = SFQ_EMPTY_SLOT;

Next message: Greg Kroah-Hartman: "[PATCH 4.9 01/72] xen-netfront: Rework the fix for Rx stall during OOM and network stress"
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