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Wen Gu c0bf3d8a94 net/smc: Transitional solution for clcsock race issue
We encountered a crash in smc_setsockopt() and it is caused by
accessing smc->clcsock after clcsock was released.

 BUG: kernel NULL pointer dereference, address: 0000000000000020
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP PTI
 CPU: 1 PID: 50309 Comm: nginx Kdump: loaded Tainted: G E     5.16.0-rc4+ #53
 RIP: 0010:smc_setsockopt+0x59/0x280 [smc]
 Call Trace:
  <TASK>
  __sys_setsockopt+0xfc/0x190
  __x64_sys_setsockopt+0x20/0x30
  do_syscall_64+0x34/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xae
 RIP: 0033:0x7f16ba83918e
  </TASK>

This patch tries to fix it by holding clcsock_release_lock and
checking whether clcsock has already been released before access.

In case that a crash of the same reason happens in smc_getsockopt()
or smc_switch_to_fallback(), this patch also checkes smc->clcsock
in them too. And the caller of smc_switch_to_fallback() will identify
whether fallback succeeds according to the return value.

Fixes: fd57770dd1 ("net/smc: wait for pending work before clcsock release_sock")
Link: https://lore.kernel.org/lkml/5dd7ffd1-28e2-24cc-9442-1defec27375e@linux.ibm.com/T/
Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-01-24 12:06:08 +00:00
Documentation Networking fixes for 5.17-rc1, including fixes from netfilter, bpf. 2022-01-20 10:57:05 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
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drivers ibmvnic: remove unused ->wait_capability 2022-01-24 12:05:03 +00:00
fs Merge branch 'akpm' (patches from Andrew) 2022-01-20 10:41:01 +02:00
include bonding: use rcu_dereference_rtnl when get bonding active slave 2022-01-24 11:57:38 +00:00
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kernel Networking fixes for 5.17-rc1, including fixes from netfilter, bpf. 2022-01-20 10:57:05 +02:00
lib Networking fixes for 5.17-rc1, including fixes from netfilter, bpf. 2022-01-20 10:57:05 +02:00
mm Merge branch 'akpm' (patches from Andrew) 2022-01-20 10:41:01 +02:00
net net/smc: Transitional solution for clcsock race issue 2022-01-24 12:06:08 +00:00
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scripts Merge branch 'akpm' (patches from Andrew) 2022-01-20 10:41:01 +02:00
security fs.idmapped.v5.17 2022-01-11 14:26:55 -08:00
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tools selftests: net: ioam: expect support for Queue depth data 2022-01-21 19:26:39 -08:00
usr kbuild: rename cmd_{bzip2,lzma,lzo,lz4,xzkern,zstd22} 2022-01-14 02:54:05 +09:00
virt RISCV: 2022-01-16 16:15:14 +02:00
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.cocciconfig
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COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Removing Ohad from remoteproc/rpmsg maintenance 2021-12-08 10:09:40 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS wireless fixes for v5.17 2022-01-21 11:23:33 +00:00
Makefile Kbuild updates for v5.17 2022-01-19 11:15:19 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

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.