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Groups > linux.kernel > #1409512
| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 4.6 071/100] Fix OpenSSH pty regression on close |
| Date | 2016-05-30 23:30 +0200 |
| Message-ID | <rECV5-1mL-55@gated-at.bofh.it> (permalink) |
| References | <rECBH-1eG-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
4.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Brian Bloniarz <brian.bloniarz@gmail.com>
commit 0f40fbbcc34e093255a2b2d70b6b0fb48c3f39aa upstream.
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 <tsi@tuyoix.net>
Reported-by: Volth <openssh@volth.com>
Reported-by: Marc Aurele La France <tsi@tuyoix.net>
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 <brian.bloniarz@gmail.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Documentation/serial/tty.txt | 3 -
drivers/tty/n_hdlc.c | 4 +-
drivers/tty/n_tty.c | 70 ++++++++++++++++++++-----------------------
drivers/tty/pty.c | 4 --
drivers/tty/tty_buffer.c | 34 +++-----------------
include/linux/tty.h | 2 -
6 files changed, 43 insertions(+), 74 deletions(-)
--- a/Documentation/serial/tty.txt
+++ b/Documentation/serial/tty.txt
@@ -210,9 +210,6 @@ TTY_IO_ERROR If set, causes all subsequ
TTY_OTHER_CLOSED Device is a pty and the other side has closed.
-TTY_OTHER_DONE Device is a pty and the other side has closed and
- all pending input processing has been completed.
-
TTY_NO_WRITE_SPLIT Prevent driver from splitting up writes into
smaller chunks.
--- a/drivers/tty/n_hdlc.c
+++ b/drivers/tty/n_hdlc.c
@@ -599,7 +599,7 @@ static ssize_t n_hdlc_tty_read(struct tt
add_wait_queue(&tty->read_wait, &wait);
for (;;) {
- if (test_bit(TTY_OTHER_DONE, &tty->flags)) {
+ if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
ret = -EIO;
break;
}
@@ -827,7 +827,7 @@ static unsigned int n_hdlc_tty_poll(stru
/* set bits for operations that won't block */
if (n_hdlc->rx_buf_list.head)
mask |= POLLIN | POLLRDNORM; /* readable */
- if (test_bit(TTY_OTHER_DONE, &tty->flags))
+ if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
mask |= POLLHUP;
if (tty_hung_up_p(filp))
mask |= POLLHUP;
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1917,18 +1917,6 @@ static inline int input_available_p(stru
return ldata->commit_head - ldata->read_tail >= amt;
}
-static inline int check_other_done(struct tty_struct *tty)
-{
- int done = test_bit(TTY_OTHER_DONE, &tty->flags);
- if (done) {
- /* paired with cmpxchg() in check_other_closed(); ensures
- * read buffer head index is not stale
- */
- smp_mb__after_atomic();
- }
- return done;
-}
-
/**
* copy_from_read_buf - copy read data directly
* @tty: terminal device
@@ -2124,7 +2112,7 @@ static ssize_t n_tty_read(struct tty_str
struct n_tty_data *ldata = tty->disc_data;
unsigned char __user *b = buf;
DEFINE_WAIT_FUNC(wait, woken_wake_function);
- int c, done;
+ int c;
int minimum, time;
ssize_t retval = 0;
long timeout;
@@ -2183,32 +2171,35 @@ static ssize_t n_tty_read(struct tty_str
break;
}
- done = check_other_done(tty);
-
if (!input_available_p(tty, 0)) {
- if (done) {
- retval = -EIO;
- break;
- }
- if (tty_hung_up_p(file))
- break;
- if (!timeout)
- break;
- if (file->f_flags & O_NONBLOCK) {
- retval = -EAGAIN;
- break;
- }
- if (signal_pending(current)) {
- retval = -ERESTARTSYS;
- break;
- }
up_read(&tty->termios_rwsem);
+ tty_buffer_flush_work(tty->port);
+ down_read(&tty->termios_rwsem);
+ if (!input_available_p(tty, 0)) {
+ if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
+ retval = -EIO;
+ break;
+ }
+ if (tty_hung_up_p(file))
+ break;
+ if (!timeout)
+ break;
+ if (file->f_flags & O_NONBLOCK) {
+ retval = -EAGAIN;
+ break;
+ }
+ if (signal_pending(current)) {
+ retval = -ERESTARTSYS;
+ break;
+ }
+ up_read(&tty->termios_rwsem);
- timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
- timeout);
+ timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
+ timeout);
- down_read(&tty->termios_rwsem);
- continue;
+ down_read(&tty->termios_rwsem);
+ continue;
+ }
}
if (ldata->icanon && !L_EXTPROC(tty)) {
@@ -2386,12 +2377,17 @@ static unsigned int n_tty_poll(struct tt
poll_wait(file, &tty->read_wait, wait);
poll_wait(file, &tty->write_wait, wait);
- if (check_other_done(tty))
- mask |= POLLHUP;
if (input_available_p(tty, 1))
mask |= POLLIN | POLLRDNORM;
+ else {
+ tty_buffer_flush_work(tty->port);
+ if (input_available_p(tty, 1))
+ mask |= POLLIN | POLLRDNORM;
+ }
if (tty->packet && tty->link->ctrl_status)
mask |= POLLPRI | POLLIN | POLLRDNORM;
+ if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
+ mask |= POLLHUP;
if (tty_hung_up_p(file))
mask |= POLLHUP;
if (tty->ops->write && !tty_is_writelocked(tty) &&
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -59,7 +59,7 @@ static void pty_close(struct tty_struct
if (!tty->link)
return;
set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
- tty_flip_buffer_push(tty->link->port);
+ wake_up_interruptible(&tty->link->read_wait);
wake_up_interruptible(&tty->link->write_wait);
if (tty->driver->subtype == PTY_TYPE_MASTER) {
set_bit(TTY_OTHER_CLOSED, &tty->flags);
@@ -247,9 +247,7 @@ static int pty_open(struct tty_struct *t
goto out;
clear_bit(TTY_IO_ERROR, &tty->flags);
- /* TTY_OTHER_CLOSED must be cleared before TTY_OTHER_DONE */
clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
- clear_bit(TTY_OTHER_DONE, &tty->link->flags);
set_bit(TTY_THROTTLED, &tty->flags);
return 0;
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -37,29 +37,6 @@
#define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF)
-/*
- * If all tty flip buffers have been processed by flush_to_ldisc() or
- * dropped by tty_buffer_flush(), check if the linked pty has been closed.
- * If so, wake the reader/poll to process
- */
-static inline void check_other_closed(struct tty_struct *tty)
-{
- unsigned long flags, old;
-
- /* transition from TTY_OTHER_CLOSED => TTY_OTHER_DONE must be atomic */
- for (flags = ACCESS_ONCE(tty->flags);
- test_bit(TTY_OTHER_CLOSED, &flags);
- ) {
- old = flags;
- __set_bit(TTY_OTHER_DONE, &flags);
- flags = cmpxchg(&tty->flags, old, flags);
- if (old == flags) {
- wake_up_interruptible(&tty->read_wait);
- break;
- }
- }
-}
-
/**
* tty_buffer_lock_exclusive - gain exclusive access to buffer
* tty_buffer_unlock_exclusive - release exclusive access
@@ -254,8 +231,6 @@ void tty_buffer_flush(struct tty_struct
if (ld && ld->ops->flush_buffer)
ld->ops->flush_buffer(tty);
- check_other_closed(tty);
-
atomic_dec(&buf->priority);
mutex_unlock(&buf->lock);
}
@@ -522,10 +497,8 @@ static void flush_to_ldisc(struct work_s
*/
count = smp_load_acquire(&head->commit) - head->read;
if (!count) {
- if (next == NULL) {
- check_other_closed(tty);
+ if (next == NULL)
break;
- }
buf->head = next;
tty_buffer_free(port, head);
continue;
@@ -614,3 +587,8 @@ bool tty_buffer_cancel_work(struct tty_p
{
return cancel_work_sync(&port->buf.work);
}
+
+void tty_buffer_flush_work(struct tty_port *port)
+{
+ flush_work(&port->buf.work);
+}
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -338,7 +338,6 @@ struct tty_file_private {
#define TTY_OTHER_CLOSED 2 /* Other side (if any) has closed */
#define TTY_EXCLUSIVE 3 /* Exclusive open mode */
#define TTY_DO_WRITE_WAKEUP 5 /* Call write_wakeup after queuing new */
-#define TTY_OTHER_DONE 6 /* Closed pty has completed input processing */
#define TTY_LDISC_OPEN 11 /* Line discipline is open */
#define TTY_PTY_LOCK 16 /* pty private */
#define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */
@@ -457,6 +456,7 @@ extern void tty_buffer_init(struct tty_p
extern void tty_buffer_set_lock_subclass(struct tty_port *port);
extern bool tty_buffer_restart_work(struct tty_port *port);
extern bool tty_buffer_cancel_work(struct tty_port *port);
+extern void tty_buffer_flush_work(struct tty_port *port);
extern speed_t tty_termios_baud_rate(struct ktermios *termios);
extern speed_t tty_termios_input_baud_rate(struct ktermios *termios);
extern void tty_termios_encode_baud_rate(struct ktermios *termios,
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[PATCH 4.6 000/100] 4.6.1-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 074/100] serial: 8250_mid: recognize interrupt source in handler Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 070/100] tty/serial: atmel: fix hardware handshake selection Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 077/100] clk: bcm2835: add locking to pll*_on/off methods Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 069/100] TTY: n_gsm, fix false positive WARN_ON Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 055/100] usb: misc: usbtest: fix pattern tests for scatterlists. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 073/100] serial: 8250_mid: use proper bar for DNV platform Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 079/100] watchdog: sp5100_tco: properly check for new register layouts Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 071/100] Fix OpenSSH pty regression on close Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 056/100] USB: leave LPM alone if possible when binding/unbinding interface drivers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 022/100] fscrypto/f2fs: allow fs-specific key prefix for fs encryption Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 076/100] locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 007/100] kvm: arm64: Fix EC field in inject_abt64 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 068/100] tty: vt, return error when con_startup fails Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 067/100] x86/cpufeature, x86/mm/pkeys: Fix broken compile-time disabling of pkeys Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 042/100] mei: amthif: discard not read messages Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 008/100] perf/x86/intel/uncore: Remove WARN_ON_ONCE in uncore_pci_probe Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
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[PATCH 4.6 081/100] Fixing oops in callback path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 059/100] usb: host: xhci-rcar: Avoid long wait in xhci_reset() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 044/100] USB: serial: cp210x: fix hardware flow-control disable Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 060/100] staging: comedi: das1800: fix possible NULL dereference Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:30 +0200
[PATCH 4.6 039/100] Bluetooth: vhci: purge unhandled skbs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:40 +0200
[PATCH 4.6 038/100] Bluetooth: vhci: fix open_timeout vs. hdev race Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:40 +0200
[PATCH 4.6 016/100] ring-buffer: Prevent overflow of size in ring_buffer_resize() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:40 +0200
[PATCH 4.6 033/100] mmc: sdhci-acpi: Remove MMC_CAP_BUS_WIDTH_TEST for Intel controllers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 037/100] mmc: sdhci-pci: Remove MMC_CAP_BUS_WIDTH_TEST for Intel controllers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 031/100] ACPI / PM: Export acpi_device_fix_up_power() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 027/100] irqchip/gic-v3: Configure all interrupts as non-secure Group-1 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 036/100] mmc: longer timeout for long read time quirk Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 020/100] clk: qcom: msm8916: Fix crypto clock flags Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 024/100] mfd: omap-usb-tll: Fix scheduling while atomic BUG Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 018/100] crypto: talitos - fix ahash algorithms registration Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 002/100] arm64: Ensure pmd_present() returns false after pmd_mknotpresent() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 025/100] Input: pwm-beeper - fix - scheduling while atomic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 026/100] irqchip/gic: Ensure ordering between read of INTACK and shared data Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 030/100] mmc: mmc: Fix partition switch timeout for some eMMCs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 003/100] arm64: Implement ptep_set_access_flags() for hardware AF/DBM Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 019/100] crypto: sun4i-ss - Replace spinlock_bh by spin_lock_irq{save|restore} Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 023/100] sched/loadavg: Fix loadavg artifacts on fully idle and on fully loaded systems Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 017/100] crypto: caam - fix caam_jr_alloc() ret code Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
[PATCH 4.6 034/100] ACPI / osi: Fix an issue that acpi_osi=!* cannot disable ACPICA internal strings Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:50 +0200
Re: [PATCH 4.6 000/100] 4.6.1-stable review Guenter Roeck <linux@roeck-us.net> - 2016-06-01 07:40 +0200
Re: [PATCH 4.6 000/100] 4.6.1-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-01 18:20 +0200
Re: [PATCH 4.6 000/100] 4.6.1-stable review "Xuetao Guan" <gxt@mprc.pku.edu.cn> - 2016-06-02 06:40 +0200
Re: [PATCH 4.6 000/100] 4.6.1-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-06-01 16:30 +0200
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