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Zhenzhong Duan 9a655c77ff ttyprintk: fix a potential deadlock in interrupt context issue
tpk_write()/tpk_close() could be interrupted when holding a mutex, then
in timer handler tpk_write() may be called again trying to acquire same
mutex, lead to deadlock.

Google syzbot reported this issue with CONFIG_DEBUG_ATOMIC_SLEEP
enabled:

BUG: sleeping function called from invalid context at
kernel/locking/mutex.c:938
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/1
1 lock held by swapper/1/0:
...
Call Trace:
  <IRQ>
  dump_stack+0x197/0x210
  ___might_sleep.cold+0x1fb/0x23e
  __might_sleep+0x95/0x190
  __mutex_lock+0xc5/0x13c0
  mutex_lock_nested+0x16/0x20
  tpk_write+0x5d/0x340
  resync_tnc+0x1b6/0x320
  call_timer_fn+0x1ac/0x780
  run_timer_softirq+0x6c3/0x1790
  __do_softirq+0x262/0x98c
  irq_exit+0x19b/0x1e0
  smp_apic_timer_interrupt+0x1a3/0x610
  apic_timer_interrupt+0xf/0x20
  </IRQ>

See link https://syzkaller.appspot.com/bug?extid=2eeef62ee31f9460ad65 for
more details.

Fix it by using spinlock in process context instead of mutex and having
interrupt disabled in critical section.

Reported-by: syzbot+2eeef62ee31f9460ad65@syzkaller.appspotmail.com
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200113034842.435-1-zhenzhong.duan@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-14 14:37:54 +01:00
arch Merge 5.5-rc6 into tty-next 2020-01-13 12:13:05 +01:00
block fs: move guard_bio_eod() after bio_set_op_attrs 2020-01-09 08:16:12 -07:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto tpmdd fixes for Linux v5.5-rc3 2019-12-18 17:17:36 -08:00
Documentation Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2020-01-11 15:40:43 -08:00
drivers ttyprintk: fix a potential deadlock in interrupt context issue 2020-01-14 14:37:54 +01:00
fs Char/Misc patch for 5.5-rc6 2020-01-10 13:25:24 -08:00
include Merge 5.5-rc6 into tty-next 2020-01-13 12:13:05 +01:00
init Revert "fs: remove ksys_dup()" 2020-01-02 16:15:33 -08:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel clone3-tls-v5.5-rc6 2020-01-11 15:33:48 -08:00
lib Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-12-22 17:00:04 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm arm64: Revert support for execute-only user mappings 2020-01-06 10:10:07 -08:00
net tipc: fix wrong connect() return code 2020-01-08 15:57:35 -08:00
samples samples/seccomp: Zero out members based on seccomp_notif_sizes 2020-01-02 13:03:39 -08:00
scripts Merge 5.5-rc6 into tty-next 2020-01-13 12:13:05 +01:00
security + Bug fixes 2020-01-04 19:28:30 -08:00
sound sound fixes for 5.5-rc6 2020-01-10 11:52:36 -08:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-09 10:34:07 -08:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-04 00:00:48 +09:00
virt PPC KVM fix for 5.5 2019-12-22 13:18:15 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-12-22 09:54:33 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Linux 5.4-rc4 2019-10-29 04:43:29 -06:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: Add myself as maintainer of ehv_bytechan tty driver 2020-01-14 14:37:54 +01:00
Makefile Linux 5.5-rc6 2020-01-12 16:55:08 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.