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authorJiri Slaby <jslaby@suse.cz>2019-05-21 08:12:57 +0200
committerJiri Slaby <jslaby@suse.cz>2019-05-21 08:12:57 +0200
commitf4a2fd2c4b49fb5206655d83f892ed414f89cf21 (patch)
treed22ddd75b4a74e94d828ae067f57249c149fcbd4
parent2e69a777ee01bf6527dc75a05394d45ed8ff5081 (diff)
TTY: serial_core, add ->install (bnc#1129693).
-rw-r--r--patches.suse/TTY-serial_core-add-install.patch128
-rw-r--r--series.conf1
2 files changed, 129 insertions, 0 deletions
diff --git a/patches.suse/TTY-serial_core-add-install.patch b/patches.suse/TTY-serial_core-add-install.patch
new file mode 100644
index 0000000000..c70ad23c1a
--- /dev/null
+++ b/patches.suse/TTY-serial_core-add-install.patch
@@ -0,0 +1,128 @@
+From: Jiri Slaby <jslaby@suse.cz>
+Date: Wed, 17 Apr 2019 10:58:53 +0200
+Subject: TTY: serial_core, add ->install
+Git-commit: 4cdd17ba1dff20ffc99fdbd2e6f0201fc7fe67df
+Patch-mainline: v5.2-rc1
+References: bnc#1129693
+
+We need to compute the uart state only on the first open. This is
+usually what is done in the ->install hook. serial_core used to do this
+in ->open on every open. So move it to ->install.
+
+As a side effect, it ensures the state is set properly in the window
+after tty_init_dev is called, but before uart_open. This fixes a bunch
+of races between tty_open and flush_to_ldisc we were dealing with
+recently.
+
+One of such bugs was attempted to fix in commit fedb5760648a (serial:
+fix race between flush_to_ldisc and tty_open), but it only took care of
+a couple of functions (uart_start and uart_unthrottle). I was able to
+reproduce the crash on a SLE system, but in uart_write_room which is
+also called from flush_to_ldisc via process_echoes. I was *unable* to
+reproduce the bug locally. It is due to having this patch in my queue
+since 2012!
+
+ general protection fault: 0000 [#1] SMP KASAN PTI
+ CPU: 1 PID: 5 Comm: kworker/u4:0 Tainted: G L 4.12.14-396-default #1 SLE15-SP1 (unreleased)
+ Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c89-prebuilt.qemu.org 04/01/2014
+ Workqueue: events_unbound flush_to_ldisc
+ task: ffff8800427d8040 task.stack: ffff8800427f0000
+ RIP: 0010:uart_write_room+0xc4/0x590
+ RSP: 0018:ffff8800427f7088 EFLAGS: 00010202
+ RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
+ RDX: 000000000000002f RSI: 00000000000000ee RDI: ffff88003888bd90
+ RBP: ffffffffb9545850 R08: 0000000000000001 R09: 0000000000000400
+ R10: ffff8800427d825c R11: 000000000000006e R12: 1ffff100084fee12
+ R13: ffffc900004c5000 R14: ffff88003888bb28 R15: 0000000000000178
+ FS: 0000000000000000(0000) GS:ffff880043300000(0000) knlGS:0000000000000000
+ CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+ CR2: 0000561da0794148 CR3: 000000000ebf4000 CR4: 00000000000006e0
+ Call Trace:
+ tty_write_room+0x6d/0xc0
+ __process_echoes+0x55/0x870
+ n_tty_receive_buf_common+0x105e/0x26d0
+ tty_ldisc_receive_buf+0xb7/0x1c0
+ tty_port_default_receive_buf+0x107/0x180
+ flush_to_ldisc+0x35d/0x5c0
+...
+
+0 in rbx means tty->driver_data is NULL in uart_write_room. 0x178 is
+tried to be dereferenced (0x178 >> 3 is 0x2f in rdx) at
+uart_write_room+0xc4. 0x178 is exactly (struct uart_state *)NULL->refcount
+used in uart_port_lock from uart_write_room.
+
+So revert the upstream commit here as my local patch should fix the
+whole family.
+
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+Cc: Li RongQing <lirongqing@baidu.com>
+Cc: Wang Li <wangli39@baidu.com>
+Cc: Zhang Yu <zhangyu31@baidu.com>
+Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Cc: stable <stable@vger.kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/tty/serial/serial_core.c | 24 +++++++++++++-----------
+ 1 file changed, 13 insertions(+), 11 deletions(-)
+
+--- a/drivers/tty/serial/serial_core.c
++++ b/drivers/tty/serial/serial_core.c
+@@ -143,9 +143,6 @@ static void uart_start(struct tty_struct
+ struct uart_port *port;
+ unsigned long flags;
+
+- if (!state)
+- return;
+-
+ port = uart_port_lock(state, flags);
+ __uart_start(tty);
+ uart_port_unlock(port, flags);
+@@ -722,9 +719,6 @@ static void uart_unthrottle(struct tty_s
+ struct uart_port *port;
+ upstat_t mask = 0;
+
+- if (!state)
+- return;
+-
+ port = uart_port_ref(state);
+ if (!port)
+ return;
+@@ -1707,6 +1701,16 @@ static void uart_dtr_rts(struct tty_port
+ uart_port_deref(uport);
+ }
+
++static int uart_install(struct tty_driver *driver, struct tty_struct *tty)
++{
++ struct uart_driver *drv = driver->driver_state;
++ struct uart_state *state = drv->state + tty->index;
++
++ tty->driver_data = state;
++
++ return tty_standard_install(driver, tty);
++}
++
+ /*
+ * Calls to uart_open are serialised by the tty_lock in
+ * drivers/tty/tty_io.c:tty_open()
+@@ -1719,11 +1723,8 @@ static void uart_dtr_rts(struct tty_port
+ */
+ static int uart_open(struct tty_struct *tty, struct file *filp)
+ {
+- struct uart_driver *drv = tty->driver->driver_state;
+- int retval, line = tty->index;
+- struct uart_state *state = drv->state + line;
+-
+- tty->driver_data = state;
++ struct uart_state *state = tty->driver_data;
++ int retval;
+
+ retval = tty_port_open(&state->port, tty, filp);
+ if (retval > 0)
+@@ -2421,6 +2422,7 @@ static void uart_poll_put_char(struct tt
+ #endif
+
+ static const struct tty_operations uart_ops = {
++ .install = uart_install,
+ .open = uart_open,
+ .close = uart_close,
+ .write = uart_write,
diff --git a/series.conf b/series.conf
index e17a490f2f..e436d581d2 100644
--- a/series.conf
+++ b/series.conf
@@ -21944,6 +21944,7 @@
patches.drivers/tty-vt.c-Fix-TIOCL_BLANKSCREEN-console-blanking-if-b.patch
patches.drivers/tty-pty-Fix-race-condition-between-release_one_tty-a.patch
patches.drivers/Revert-tty-pty-Fix-race-condition-between-release_on.patch
+ patches.suse/TTY-serial_core-add-install.patch
patches.drivers/ipmi-ssif-compare-block-number-correctly-for-multi-p.patch
patches.drivers/media-ivtv-update-pos-correctly-in-ivtv_read_pos.patch
patches.drivers/media-cx18-update-pos-correctly-in-cx18_read_pos.patch