user/sven/linux.git/include/linux/tty.h, branch v4.9.188

tty: Don't call panic() at tty_ldisc_init()

2018-05-01T22:13:05Z

commit 903f9db10f18f735e62ba447147b6c434b6af003 upstream. syzbot is reporting kernel panic [1] triggered by memory allocation failure at tty_ldisc_get() from tty_ldisc_init(). But since both tty_ldisc_get() and caller of tty_ldisc_init() can cleanly handle errors, tty_ldisc_init() does not need to call panic() when tty_ldisc_get() failed. [1] https://syzkaller.appspot.com/bug?id=883431818e036ae6a9981156a64b821110f39187 Signed-off-by: Tetsuo Handa Reported-by: syzbot Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: make n_tty_read() always abort if hangup is in progress

2018-04-24T07:34:08Z

commit 28b0f8a6962a24ed21737578f3b1b07424635c9e upstream. A tty is hung up by __tty_hangup() setting file->f_op to hung_up_tty_fops, which is skipped on ttys whose write operation isn't tty_write(). This means that, for example, /dev/console whose write op is redirected_tty_write() is never actually marked hung up. Because n_tty_read() uses the hung up status to decide whether to abort the waiting readers, the lack of hung-up marking can lead to the following scenario. 1. A session contains two processes. The leader and its child. The child ignores SIGHUP. 2. The leader exits and starts disassociating from the controlling terminal (/dev/console). 3. __tty_hangup() skips setting f_op to hung_up_tty_fops. 4. SIGHUP is delivered and ignored. 5. tty_ldisc_hangup() is invoked. It wakes up the waits which should clear the read lockers of tty->ldisc_sem. 6. The reader wakes up but because tty_hung_up_p() is false, it doesn't abort and goes back to sleep while read-holding tty->ldisc_sem. 7. The leader progresses to tty_ldisc_lock() in tty_ldisc_hangup() and is now stuck in D sleep indefinitely waiting for tty->ldisc_sem. The following is Alan's explanation on why some ttys aren't hung up. http://lkml.kernel.org/r/20171101170908.6ad08580@alans-desktop 1. It broke the serial consoles because they would hang up and close down the hardware. With tty_port that *should* be fixable properly for any cases remaining. 2. The console layer was (and still is) completely broken and doens't refcount properly. So if you turn on console hangups it breaks (as indeed does freeing consoles and half a dozen other things). As neither can be fixed quickly, this patch works around the problem by introducing a new flag, TTY_HUPPING, which is used solely to tell n_tty_read() that hang-up is in progress for the console and the readers should be aborted regardless of the hung-up status of the device. The following is a sample hung task warning caused by this issue. INFO: task agetty:2662 blocked for more than 120 seconds. Not tainted 4.11.3-dbg-tty-lockup-02478-gfd6c7ee-dirty #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. 0 2662 1 0x00000086 Call Trace: __schedule+0x267/0x890 schedule+0x36/0x80 schedule_timeout+0x23c/0x2e0 ldsem_down_write+0xce/0x1f6 tty_ldisc_lock+0x16/0x30 tty_ldisc_hangup+0xb3/0x1b0 __tty_hangup+0x300/0x410 disassociate_ctty+0x6c/0x290 do_exit+0x7ef/0xb00 do_group_exit+0x3f/0xa0 get_signal+0x1b3/0x5d0 do_signal+0x28/0x660 exit_to_usermode_loop+0x46/0x86 do_syscall_64+0x9c/0xb0 entry_SYSCALL64_slow_path+0x25/0x25 The following is the repro. Run "$PROG /dev/console". The parent process hangs in D state. #include #include #include #include #include #include #include #include #include #include #include #include int main(int argc, char **argv) { struct sigaction sact = { .sa_handler = SIG_IGN }; struct timespec ts1s = { .tv_sec = 1 }; pid_t pid; int fd; if (argc < 2) { fprintf(stderr, "test-hung-tty /dev/$TTY\n"); return 1; } /* fork a child to ensure that it isn't already the session leader */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { /* top parent, wait for everyone */ while (waitpid(-1, NULL, 0) >= 0) ; if (errno != ECHILD) perror("waitpid"); return 0; } /* new session, start a new session and set the controlling tty */ if (setsid() < 0) { perror("setsid"); return 1; } fd = open(argv[1], O_RDWR); if (fd < 0) { perror("open"); return 1; } if (ioctl(fd, TIOCSCTTY, 1) < 0) { perror("ioctl"); return 1; } /* fork a child, sleep a bit and exit */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { nanosleep(&ts1s, NULL); printf("Session leader exiting\n"); exit(0); } /* * The child ignores SIGHUP and keeps reading from the controlling * tty. Because SIGHUP is ignored, the child doesn't get killed on * parent exit and the bug in n_tty makes the read(2) block the * parent's control terminal hangup attempt. The parent ends up in * D sleep until the child is explicitly killed. */ sigaction(SIGHUP, &sact, NULL); printf("Child reading tty\n"); while (1) { char buf[1024]; if (read(fd, buf, sizeof(buf)) < 0) { perror("read"); return 1; } } return 0; } Signed-off-by: Tejun Heo Cc: Alan Cox Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

tty: fix data race between tty_init_dev and flush of buf

2018-02-03T16:05:41Z

commit b027e2298bd588d6fa36ed2eda97447fb3eac078 upstream. There can be a race, if receive_buf call comes before tty initialization completes in n_tty_open and tty->disc_data may be NULL. CPU0 CPU1 ---- ---- 000|n_tty_receive_buf_common() n_tty_open() -001|n_tty_receive_buf2() tty_ldisc_open.isra.3() -002|tty_ldisc_receive_buf(inline) tty_ldisc_setup() Using ldisc semaphore lock in tty_init_dev till disc_data initializes completely. Signed-off-by: Gaurav Kohli Reviewed-by: Alan Cox Signed-off-by: Greg Kroah-Hartman

Merge tag 'tty-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2016-05-21T03:57:27Z

Pull tty and serial driver updates from Greg KH: "Here's the large TTY and Serial driver update for 4.7-rc1. A few new serial drivers are added here, and Peter has fixed a bunch of long-standing bugs in the tty layer and serial drivers as normal. Full details in the shortlog. All of these have been in linux-next for a while with no reported issues" * tag 'tty-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (88 commits) MAINTAINERS: 8250: remove website reference serial: core: Fix port mutex assert if lockdep disabled serial: 8250_dw: fix wrong logic in dw8250_check_lcr() tty: vt, finish looping on duplicate tty: vt, return error when con_startup fails QE-UART: add "fsl,t1040-ucc-uart" to of_device_id serial: mctrl_gpio: Drop support for out1-gpios and out2-gpios serial: 8250dw: Add device HID for future AMD UART controller Fix OpenSSH pty regression on close serial: mctrl_gpio: add IRQ locking serial: 8250: Integrate Fintek into 8250_base serial: mps2-uart: add support for early console serial: mps2-uart: add MPS2 UART driver dt-bindings: document the MPS2 UART bindings serial: sirf: Use generic uart-has-rtscts DT property serial: sirf: Introduce helper variable struct device_node *np serial: mxs-auart: Use generic uart-has-rtscts DT property serial: imx: Use generic uart-has-rtscts DT property doc: DT: Add Generic Serial Device Tree Bindings serial: 8250: of: Make tegra_serial_handle_break() static ...

Merge branch 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit

2016-05-19T01:46:55Z

Pull audit updates from Paul Moore: "Four small audit patches for 4.7. Two are simple cleanups around the audit thread management code, one adds a tty field to AUDIT_LOGIN events, and the final patch makes tty_name() usable regardless of CONFIG_TTY. Nothing controversial, and it all passes our regression test" * 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit: tty: provide tty_name() even without CONFIG_TTY audit: add tty field to LOGIN event audit: we don't need to __set_current_state(TASK_RUNNING) audit: cleanup prune_tree_thread

Fix OpenSSH pty regression on close

2016-05-01T20:22:54Z

OpenSSH expects the (non-blocking) read() of pty master to return EAGAIN only if it has received all of the slave-side output after it has received SIGCHLD. This used to work on pre-3.12 kernels. This fix effectively forces non-blocking read() and poll() to block for parallel i/o to complete for all ttys. It also unwinds these changes: 1) f8747d4a466ab2cafe56112c51b3379f9fdb7a12 tty: Fix pty master read() after slave closes 2) 52bce7f8d4fc633c9a9d0646eef58ba6ae9a3b73 pty, n_tty: Simplify input processing on final close 3) 1a48632ffed61352a7810ce089dc5a8bcd505a60 pty: Fix input race when closing Inspired by analysis and patch from Marc Aurele La France Reported-by: Volth Reported-by: Marc Aurele La France BugLink: https://bugzilla.mindrot.org/show_bug.cgi?id=52 BugLink: https://bugzilla.mindrot.org/show_bug.cgi?id=2492 Signed-off-by: Brian Bloniarz Reviewed-by: Peter Hurley Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: Replace ASYNC_INITIALIZED bit and update atomically

2016-04-30T16:26:55Z

Replace ASYNC_INITIALIZED bit in the tty_port::flags field with TTY_PORT_INITIALIZED bit in the tty_port::iflags field. Introduce helpers tty_port_set_initialized() and tty_port_initialized() to abstract atomic bit ops. Note: the transforms for test_and_set_bit() and test_and_clear_bit() are unnecessary as the state transitions are already mutually exclusive; the tty lock prevents concurrent open/close/hangup. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Replace ASYNC_SUSPENDED bit and update atomically

2016-04-30T16:26:55Z

Replace ASYNC_SUSPENDED bit in the tty_port::flags field with TTY_PORT_SUSPENDED bit in the tty_port::iflags field. Introduce helpers tty_port_set_suspended() and tty_port_suspended() to abstract atomic bit ops. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Replace ASYNC_CHECK_CD and update atomically

2016-04-30T16:26:55Z

Replace ASYNC_CHECK_CD bit in the tty_port::flags field with TTY_PORT_CHECK_CD bit in the tty_port::iflags field. Introduce helpers tty_port_set_check_carrier() and tty_port_check_carrier() to abstract the atomic bit ops. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Replace ASYNC_NORMAL_ACTIVE bit and update atomically

2016-04-30T16:26:55Z

Replace ASYNC_NORMAL_ACTIVE bit in the tty_port::flags field with TTY_PORT_ACTIVE bit in the tty_port::iflags field. Introduce helpers tty_port_set_active() and tty_port_active() to abstract atomic bit ops. Extract state changes from port lock sections, as this usage is broken and confused; the state transitions are protected by the tty lock (which mutually excludes parallel open/close/hangup), and no user tests the active state while holding the port lock. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman