From: Matteo Croce mcroce@redhat.com
[ Upstream commit 25426043ec9e22b90c789407c28e40f32a9d1985 ]
When a matchall classifier is added, there is a small time interval in which tp->root is NULL. If we receive a packet in this small time slice a NULL pointer dereference will happen, leading to a kernel panic:
# tc qdisc replace dev eth0 ingress # tc filter add dev eth0 parent ffff: matchall action gact drop Unable to handle kernel NULL pointer dereference at virtual address 0000000000000034 Mem abort info: ESR = 0x96000005 Exception class = DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000005 CM = 0, WnR = 0 user pgtable: 4k pages, 39-bit VAs, pgdp = 00000000a623d530 [0000000000000034] pgd=0000000000000000, pud=0000000000000000 Internal error: Oops: 96000005 [#1] SMP Modules linked in: cls_matchall sch_ingress nls_iso8859_1 nls_cp437 vfat fat m25p80 spi_nor mtd xhci_plat_hcd xhci_hcd phy_generic sfp mdio_i2c usbcore i2c_mv64xxx marvell10g mvpp2 usb_common spi_orion mvmdio i2c_core sbsa_gwdt phylink ip_tables x_tables autofs4 Process ksoftirqd/0 (pid: 9, stack limit = 0x0000000009de7d62) CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 5.1.0-rc6 #21 Hardware name: Marvell 8040 MACCHIATOBin Double-shot (DT) pstate: 40000005 (nZcv daif -PAN -UAO) pc : mall_classify+0x28/0x78 [cls_matchall] lr : tcf_classify+0x78/0x138 sp : ffffff80109db9d0 x29: ffffff80109db9d0 x28: ffffffc426058800 x27: 0000000000000000 x26: ffffffc425b0dd00 x25: 0000000020000000 x24: 0000000000000000 x23: ffffff80109dbac0 x22: 0000000000000001 x21: ffffffc428ab5100 x20: ffffffc425b0dd00 x19: ffffff80109dbac0 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: ffffffbf108ad288 x12: dead000000000200 x11: 00000000f0000000 x10: 0000000000000001 x9 : ffffffbf1089a220 x8 : 0000000000000001 x7 : ffffffbebffaa950 x6 : 0000000000000000 x5 : 000000442d6ba000 x4 : 0000000000000000 x3 : ffffff8008735ad8 x2 : ffffff80109dbac0 x1 : ffffffc425b0dd00 x0 : ffffff8010592078 Call trace: mall_classify+0x28/0x78 [cls_matchall] tcf_classify+0x78/0x138 __netif_receive_skb_core+0x29c/0xa20 __netif_receive_skb_one_core+0x34/0x60 __netif_receive_skb+0x28/0x78 netif_receive_skb_internal+0x2c/0xc0 napi_gro_receive+0x1a0/0x1d8 mvpp2_poll+0x928/0xb18 [mvpp2] net_rx_action+0x108/0x378 __do_softirq+0x128/0x320 run_ksoftirqd+0x44/0x60 smpboot_thread_fn+0x168/0x1b0 kthread+0x12c/0x130 ret_from_fork+0x10/0x1c Code: aa0203f3 aa1e03e0 d503201f f9400684 (b9403480) ---[ end trace fc71e2ef7b8ab5a5 ]--- Kernel panic - not syncing: Fatal exception in interrupt SMP: stopping secondary CPUs Kernel Offset: disabled CPU features: 0x002,00002000 Memory Limit: none Rebooting in 1 seconds..
Fix this by adding a NULL check in mall_classify().
Fixes: ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex") Signed-off-by: Matteo Croce mcroce@redhat.com Acked-by: Cong Wang xiyou.wangcong@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/cls_matchall.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/sched/cls_matchall.c +++ b/net/sched/cls_matchall.c @@ -32,6 +32,9 @@ static int mall_classify(struct sk_buff { struct cls_mall_head *head = rcu_dereference_bh(tp->root);
+ if (unlikely(!head)) + return -1; + if (tc_skip_sw(head->flags)) return -1;