diff options
| author | Christoph Paasch <cpaasch@apple.com> | 2018-11-29 16:01:04 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-11-29 16:27:27 -0800 |
| commit | 9410d386d0a829ace9558336263086c2fbbe8aed (patch) | |
| tree | 03dcb303977b67409713f7d37a62f161fdadf8ae /net/sched | |
| parent | b020fcf6bb4b2d980298c416b3f407075aa2b3b6 (diff) | |
| download | linux-9410d386d0a829ace9558336263086c2fbbe8aed.tar.bz2 | |
net: Prevent invalid access to skb->prev in __qdisc_drop_all
__qdisc_drop_all() accesses skb->prev to get to the tail of the
segment-list.
With commit 68d2f84a1368 ("net: gro: properly remove skb from list")
the skb-list handling has been changed to set skb->next to NULL and set
the list-poison on skb->prev.
With that change, __qdisc_drop_all() will panic when it tries to
dereference skb->prev.
Since commit 992cba7e276d ("net: Add and use skb_list_del_init().")
__list_del_entry is used, leaving skb->prev unchanged (thus,
pointing to the list-head if it's the first skb of the list).
This will make __qdisc_drop_all modify the next-pointer of the list-head
and result in a panic later on:
[ 34.501053] general protection fault: 0000 [#1] SMP KASAN PTI
[ 34.501968] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.20.0-rc2.mptcp #108
[ 34.502887] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.5.1 01/01/2011
[ 34.504074] RIP: 0010:dev_gro_receive+0x343/0x1f90
[ 34.504751] Code: e0 48 c1 e8 03 42 80 3c 30 00 0f 85 4a 1c 00 00 4d 8b 24 24 4c 39 65 d0 0f 84 0a 04 00 00 49 8d 7c 24 38 48 89 f8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 74 08 3c 04
[ 34.507060] RSP: 0018:ffff8883af507930 EFLAGS: 00010202
[ 34.507761] RAX: 0000000000000007 RBX: ffff8883970b2c80 RCX: 1ffff11072e165a6
[ 34.508640] RDX: 1ffff11075867008 RSI: ffff8883ac338040 RDI: 0000000000000038
[ 34.509493] RBP: ffff8883af5079d0 R08: ffff8883970b2d40 R09: 0000000000000062
[ 34.510346] R10: 0000000000000034 R11: 0000000000000000 R12: 0000000000000000
[ 34.511215] R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8883ac338008
[ 34.512082] FS: 0000000000000000(0000) GS:ffff8883af500000(0000) knlGS:0000000000000000
[ 34.513036] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 34.513741] CR2: 000055ccc3e9d020 CR3: 00000003abf32000 CR4: 00000000000006e0
[ 34.514593] Call Trace:
[ 34.514893] <IRQ>
[ 34.515157] napi_gro_receive+0x93/0x150
[ 34.515632] receive_buf+0x893/0x3700
[ 34.516094] ? __netif_receive_skb+0x1f/0x1a0
[ 34.516629] ? virtnet_probe+0x1b40/0x1b40
[ 34.517153] ? __stable_node_chain+0x4d0/0x850
[ 34.517684] ? kfree+0x9a/0x180
[ 34.518067] ? __kasan_slab_free+0x171/0x190
[ 34.518582] ? detach_buf+0x1df/0x650
[ 34.519061] ? lapic_next_event+0x5a/0x90
[ 34.519539] ? virtqueue_get_buf_ctx+0x280/0x7f0
[ 34.520093] virtnet_poll+0x2df/0xd60
[ 34.520533] ? receive_buf+0x3700/0x3700
[ 34.521027] ? qdisc_watchdog_schedule_ns+0xd5/0x140
[ 34.521631] ? htb_dequeue+0x1817/0x25f0
[ 34.522107] ? sch_direct_xmit+0x142/0xf30
[ 34.522595] ? virtqueue_napi_schedule+0x26/0x30
[ 34.523155] net_rx_action+0x2f6/0xc50
[ 34.523601] ? napi_complete_done+0x2f0/0x2f0
[ 34.524126] ? kasan_check_read+0x11/0x20
[ 34.524608] ? _raw_spin_lock+0x7d/0xd0
[ 34.525070] ? _raw_spin_lock_bh+0xd0/0xd0
[ 34.525563] ? kvm_guest_apic_eoi_write+0x6b/0x80
[ 34.526130] ? apic_ack_irq+0x9e/0xe0
[ 34.526567] __do_softirq+0x188/0x4b5
[ 34.527015] irq_exit+0x151/0x180
[ 34.527417] do_IRQ+0xdb/0x150
[ 34.527783] common_interrupt+0xf/0xf
[ 34.528223] </IRQ>
This patch makes sure that skb->prev is set to NULL when entering
netem_enqueue.
Cc: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Fixes: 68d2f84a1368 ("net: gro: properly remove skb from list")
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Christoph Paasch <cpaasch@apple.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched')
| -rw-r--r-- | net/sched/sch_netem.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index 2c38e3d07924..22cd46a60057 100644 --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -431,6 +431,9 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch, int count = 1; int rc = NET_XMIT_SUCCESS; + /* Do not fool qdisc_drop_all() */ + skb->prev = NULL; + /* Random duplication */ if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor)) ++count; |