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25426043ec
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: ed76f5edcc ("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.