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linux/drivers/char
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Tetsuo Handa aafb5e38e6 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 09:44:23 +02:00
..
agp
parisc: parisc-agp requires SBA IOMMU driver
2021-04-14 08:24:11 +02:00
hw_random
hwrng: timeriomem - Fix cooldown period calculation
2021-03-04 10:26:24 +01:00
ipmi
ipmi_si: Fix wrong return value in try_smi_init()
2020-10-29 09:57:44 +01:00
mwave
treewide: Add SPDX license identifier - Makefile/Kconfig
2019-05-21 10:50:46 +02:00
pcmcia
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 18
2019-05-21 11:28:46 +02:00
tpm
tpm: vtpm_proxy: Avoid reading host log when using a virtual device
2021-05-11 14:04:15 +02:00
xilinx_hwicap
treewide: Add SPDX license identifier - Makefile/Kconfig
2019-05-21 10:50:46 +02:00
xillybus
PCI: Move ASPM declarations to linux/pci.h
2019-08-28 08:28:39 -05:00
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
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
applicom.h
…
bsr.c
Merge 5.2-rc4 into char-misc-next
2019-06-09 09:11:21 +02:00
ds1620.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
dsp56k.c
vfs: do bulk POLL* -> EPOLL* replacement
2018-02-11 14:34:03 -08:00
dtlk.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
efirtc.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
2020-02-24 08:36:59 +01:00
Kconfig
ia64 for v5.4 - big change here is removal of support for SGI Altix
2019-09-16 15:32:01 -07:00
lp.c
lp: fix sparc64 LPSETTIMEOUT ioctl
2019-12-13 08:42:17 +01:00
Makefile
char: remove the SGI tiocx/mbcs driver
2019-08-16 11:33:56 -07:00
mem.c
/dev/mem: Add missing memory barriers for devmem_inode
2020-07-29 10:18:43 +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: remove SGI SN2 support
2019-08-16 11:33:56 -07:00
nsc_gpio.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
nvram.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
nwbutton.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
nwbutton.h
treewide: Switch DEFINE_TIMER callbacks to struct timer_list *
2017-11-21 15:57:05 -08:00
nwflash.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
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: fix PPGETTIME/PPSETTIME ioctls
2019-12-17 19:56:41 +01:00
ps3flash.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 164
2019-05-30 11:26:38 -07:00
random.c
random: fix the RNDRESEEDCRNG ioctl
2021-03-04 10:26:11 +01:00
raw.c
treewide: Add SPDX license identifier for more missed files
2019-05-21 10:50:45 +02:00
rtc.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152
2019-05-30 11:26:32 -07:00
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
2020-10-01 13:17:56 +02:00
toshiba.c
toshiba: Add correct printk log level while emitting error log
2019-09-04 13:42:43 +02:00
ttyprintk.c
ttyprintk: Add TTY hangup callback.
2021-05-14 09:44:23 +02:00
uv_mmtimer.c
…
virtio_console.c
virtio: virtio_console: fix DMA memory allocation for rproc serial
2020-11-18 19:20:29 +01:00