aafb5e38e6
[ 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:
|
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.