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c0070e1e60
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:
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||
---|---|---|
.. | ||
agp | ||
hw_random | ||
ipmi | ||
mwave | ||
pcmcia | ||
tpm | ||
xilinx_hwicap | ||
xillybus | ||
adi.c | ||
apm-emulation.c | ||
applicom.c | ||
applicom.h | ||
bsr.c | ||
ds1620.c | ||
dsp56k.c | ||
dtlk.c | ||
hangcheck-timer.c | ||
hpet.c | ||
Kconfig | ||
lp.c | ||
Makefile | ||
mem.c | ||
misc.c | ||
mspec.c | ||
nsc_gpio.c | ||
nvram.c | ||
nwbutton.c | ||
nwbutton.h | ||
nwflash.c | ||
pc8736x_gpio.c | ||
powernv-op-panel.c | ||
ppdev.c | ||
ps3flash.c | ||
random.c | ||
raw.c | ||
scx200_gpio.c | ||
sonypi.c | ||
tb0219.c | ||
tlclk.c | ||
toshiba.c | ||
ttyprintk.c | ||
uv_mmtimer.c | ||
virtio_console.c |