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linux/drivers/char
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Tetsuo Handa 927162c713 ttyprintk: Add TTY hangup callback. 
[ Upstream commit c0070e1e60270f6a1e09442a9ab2335f3eaeaad2 ]

syzbot is reporting hung task due to flood of

  tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,
           port->count);

message [1], for ioctl(TIOCVHANGUP) prevents tty_port_close() from
decrementing port->count due to tty_hung_up_p() == true.

----------
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
	int i;
	int fd[10];

	for (i = 0; i < 10; i++)
		fd[i] = open("/dev/ttyprintk", O_WRONLY);
	ioctl(fd[0], TIOCVHANGUP);
	for (i = 0; i < 10; i++)
		close(fd[i]);
	close(open("/dev/ttyprintk", O_WRONLY));
	return 0;
}
----------

When TTY hangup happens, port->count needs to be reset via
"struct tty_operations"->hangup callback.

[1] https://syzkaller.appspot.com/bug?id=39ea6caa479af471183997376dc7e90bc7d64a6a

Reported-by: syzbot <syzbot+43e93968b964e369db0b@syzkaller.appspotmail.com>
Reported-by: syzbot <syzbot+3ed715090790806d8b18@syzkaller.appspotmail.com>
Tested-by: syzbot <syzbot+43e93968b964e369db0b@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Fixes: 24b4b67d17c308aa ("add ttyprintk driver")
Link: https://lore.kernel.org/r/17e0652d-89b7-c8c0-fb53-e7566ac9add4@i-love.sakura.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-05-14 09:50:21 +02:00
..
agp
parisc: parisc-agp requires SBA IOMMU driver
2021-04-14 08:41:59 +02:00
hw_random
hwrng: timeriomem - Fix cooldown period calculation
2021-03-04 11:37:49 +01:00
ipmi
Bug fix pull for IPMI for 5.10
2020-10-14 15:00:20 -07:00
mwave
char/mwave: remove redundant initialization of variable bRC
2020-07-10 14:50:51 +02:00
pcmcia
cm4000_cs.c cmm_ioctl(): get rid of pointless access_ok()
2020-05-29 11:04:56 -04:00
tpm
tpm: vtpm_proxy: Avoid reading host log when using a virtual device
2021-05-11 14:47:35 +02:00
xilinx_hwicap
treewide: Add SPDX license identifier - Makefile/Kconfig
2019-05-21 10:50:46 +02:00
xillybus
char: xillybus: use devm_platform_ioremap_resource() to simplify code
2019-11-05 18:29:21 +01:00
adi.c
char: sparc64: Add privileged ADI driver
2018-06-05 11:24:55 -07:00
apm-emulation.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
applicom.c
misc: cleanup minor number definitions in c file into miscdevice.h
2020-03-18 12:27:03 +01:00
applicom.h
…
bsr.c
mm: don't include asm/pgtable.h if linux/mm.h is already included
2020-06-09 09:39:13 -07:00
ds1620.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
dsp56k.c
…
dtlk.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
hangcheck-timer.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 405
2019-06-05 17:37:13 +02:00
hpet.c
char: hpet: Fix out-of-bounds read bug
2020-01-30 06:58:33 +01:00
Kconfig
char: virtio: Select VIRTIO from VIRTIO_CONSOLE.
2020-09-07 14:32:40 +02:00
lp.c
Merge 5.9-rc3 into char-misc-next
2020-08-31 07:17:17 +02:00
Makefile
rtc/alpha: remove legacy rtc driver
2020-03-19 07:41:02 +01:00
mem.c
/dev/zero: fixups for ->read
2020-09-07 10:46:35 +02:00
misc.c
char: misc: Move EXPORT_SYMBOL immediately next to the functions/varibles
2019-05-24 18:00:41 +02:00
mspec.c
char: mspec: Use kvzalloc() in mspec_mmap()
2020-08-28 12:10:04 +02:00
nsc_gpio.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
nvram.c
treewide: Use fallthrough pseudo-keyword
2020-08-23 17:36:59 -05:00
nwbutton.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
nwbutton.h
misc: cleanup minor number definitions in c file into miscdevice.h
2020-03-18 12:27:03 +01:00
nwflash.c
misc: move FLASH_MINOR into miscdevice.h and fix conflicts
2020-03-18 12:27:04 +01:00
pc8736x_gpio.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
powernv-op-panel.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
ppdev.c
ppdev: Distribute switch variables for initialization
2020-02-23 20:28:12 +01:00
ps3flash.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 164
2019-05-30 11:26:38 -07:00
random.c
random: initialize ChaCha20 constants with correct endianness
2021-05-11 14:47:19 +02:00
raw.c
raw: don't keep unopened block device around
2020-09-23 10:43:19 -06:00
scx200_gpio.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
sonypi.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61
2019-05-24 17:36:45 +02:00
tb0219.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156
2019-05-30 11:26:35 -07:00
tlclk.c
drivers: char: tlclk.c: Avoid data race between init and interrupt handler
2020-04-23 16:55:24 +02:00
toshiba.c
misc: cleanup minor number definitions in c file into miscdevice.h
2020-03-18 12:27:03 +01:00
ttyprintk.c
ttyprintk: Add TTY hangup callback.
2021-05-14 09:50:21 +02:00
uv_mmtimer.c
…
virtio_console.c
virtio: virtio_console: fix DMA memory allocation for rproc serial
2020-11-09 18:03:33 +01:00