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Filename Latest commit message Latest commit date
Ido Schimmel 7387dbbcdb mlxsw: spectrum_router: Fix use-after-free in route replace
While working on IPv6 route replace I realized we can have a
use-after-free in IPv4 in case the replaced route is offloaded and the
only one using its FIB info.

The problem is that fib_table_insert() drops the reference on the FIB
info of the replaced routes which is eventually freed via call_rcu().
Since the driver doesn't hold a reference on this FIB info it can cause
a use-after-free when it tries to clear the RTNH_F_OFFLOAD flag stored
in fi->fib_flags.

After running the following commands in a loop for enough time with a
KASAN enabled kernel I finally got the below trace.

$ ip route add 192.168.50.0/24 via 192.168.200.1 dev enp3s0np3
$ ip route replace 192.168.50.0/24 dev enp3s0np5
$ ip route del 192.168.50.0/24 dev enp3s0np5

BUG: KASAN: use-after-free in mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
Read of size 4 at addr ffff8803717d9820 by task kworker/u4:2/55
[...]
? mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
? mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
? mlxsw_sp_router_neighs_update_work+0x1cd0/0x1ce0 [mlxsw_spectrum]
? mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
__asan_load4+0x61/0x80
mlxsw_sp_fib_entry_offload_unset+0xa7/0x120 [mlxsw_spectrum]
mlxsw_sp_fib_entry_offload_refresh+0xb6/0x370 [mlxsw_spectrum]
mlxsw_sp_router_fib_event_work+0xd1c/0x2780 [mlxsw_spectrum]
[...]
Freed by task 5131:
 save_stack_trace+0x16/0x20
 save_stack+0x46/0xd0
 kasan_slab_free+0x70/0xc0
 kfree+0x144/0x570
 free_fib_info_rcu+0x2e7/0x410
 rcu_process_callbacks+0x4f8/0xe30
 __do_softirq+0x1d3/0x9e2

Fix this by taking a reference on the FIB info when creating the nexthop
group it represents and drop it when the group is destroyed.

Fixes: 599cf8f95f ("mlxsw: spectrum_router: Add support for route replace")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-12 08:15:52 -07:00
arch pci-v4.13-changes 2017-07-08 15:51:57 -07:00
block Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-06 20:57:13 -07:00
certs
crypto dmaengine updates for 4.13-rc1 2017-07-08 12:36:50 -07:00
Documentation net: Fix minor code bug in timestamping.txt 2017-07-11 13:34:54 -07:00
drivers mlxsw: spectrum_router: Fix use-after-free in route replace 2017-07-12 08:15:52 -07:00
firmware
fs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-08 10:50:54 -07:00
include pci-v4.13-changes 2017-07-08 15:51:57 -07:00
init mm: allow slab_nomerge to be set at build time 2017-07-06 16:24:31 -07:00
ipc Writeback error handling fixes (pile #1) 2017-07-07 18:39:15 -07:00
kernel pci-v4.13-changes 2017-07-08 15:51:57 -07:00
lib dmaengine updates for 4.13-rc1 2017-07-08 12:36:50 -07:00
mm Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-07-08 12:17:25 -07:00
net bridge: mdb: fix leak on complete_info ptr on fail path 2017-07-11 20:01:39 -07:00
samples samples/bpf: fix a build issue 2017-07-11 20:51:29 -07:00
scripts Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
security Merge branch 'work.memdup_user' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-05 16:05:24 -07:00
sound sound updates for 4.13-rc1 2017-07-06 10:56:51 -07:00
tools samples/bpf: fix a build issue 2017-07-11 20:51:29 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt PPC: 2017-07-06 18:38:31 -07:00
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MAINTAINERS pci-v4.13-changes 2017-07-08 15:51:57 -07:00
Makefile Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.