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Commit 68d91b4c79481099b0fe0b37c7eafeabd12813ae

Authored by Johan Hovold
Committed by Greg Kroah-Hartman
1 parent f33e402782

USB: console: fix uninitialised ldisc semaphore 

commit d269d4434c72ed0da3a9b1230c30da82c4918c63 upstream.

The USB console currently allocates a temporary fake tty which is used
to pass terminal settings to the underlying serial driver.

The tty struct is not fully initialised, something which can lead to a
lockdep warning (or worse) if a serial driver tries to acquire a
line-discipline reference:

	usbserial: USB Serial support registered for pl2303
	pl2303 1-2.1:1.0: pl2303 converter detected
	usb 1-2.1: pl2303 converter now attached to ttyUSB0
	INFO: trying to register non-static key.
	the code is fine but needs lockdep annotation.
	turning off the locking correctness validator.
	CPU: 0 PID: 68 Comm: udevd Tainted: G        W      3.18.0-rc5 #10
	[<c0016f04>] (unwind_backtrace) from [<c0013978>] (show_stack+0x20/0x24)
	[<c0013978>] (show_stack) from [<c0449794>] (dump_stack+0x24/0x28)
	[<c0449794>] (dump_stack) from [<c006f730>] (__lock_acquire+0x1e50/0x2004)
	[<c006f730>] (__lock_acquire) from [<c0070128>] (lock_acquire+0xe4/0x18c)
	[<c0070128>] (lock_acquire) from [<c027c6f8>] (ldsem_down_read_trylock+0x78/0x90)
	[<c027c6f8>] (ldsem_down_read_trylock) from [<c027a1cc>] (tty_ldisc_ref+0x24/0x58)
	[<c027a1cc>] (tty_ldisc_ref) from [<c0340760>] (usb_serial_handle_dcd_change+0x48/0xe8)
	[<c0340760>] (usb_serial_handle_dcd_change) from [<bf000484>] (pl2303_read_int_callback+0x210/0x220 [pl2303])
	[<bf000484>] (pl2303_read_int_callback [pl2303]) from [<c031624c>] (__usb_hcd_giveback_urb+0x80/0x140)
	[<c031624c>] (__usb_hcd_giveback_urb) from [<c0316fc0>] (usb_giveback_urb_bh+0x98/0xd4)
	[<c0316fc0>] (usb_giveback_urb_bh) from [<c0042e44>] (tasklet_hi_action+0x9c/0x108)
	[<c0042e44>] (tasklet_hi_action) from [<c0042380>] (__do_softirq+0x148/0x42c)
	[<c0042380>] (__do_softirq) from [<c00429cc>] (irq_exit+0xd8/0x114)
	[<c00429cc>] (irq_exit) from [<c007ae58>] (__handle_domain_irq+0x84/0xdc)
	[<c007ae58>] (__handle_domain_irq) from [<c000879c>] (omap_intc_handle_irq+0xd8/0xe0)
	[<c000879c>] (omap_intc_handle_irq) from [<c0014544>] (__irq_svc+0x44/0x7c)
	Exception stack(0xdf4e7f08 to 0xdf4e7f50)
	7f00:                   debc0b80 df4e7f5c 00000000 00000000 debc0b80 be8da96c
	7f20: 00000000 00000128 c000fc84 df4e6000 00000000 df4e7f94 00000004 df4e7f50
	7f40: c038ebc0 c038d74c 600f0013 ffffffff
	[<c0014544>] (__irq_svc) from [<c038d74c>] (___sys_sendmsg.part.29+0x0/0x2e0)
	[<c038d74c>] (___sys_sendmsg.part.29) from [<c038ec08>] (SyS_sendmsg+0x18/0x1c)
	[<c038ec08>] (SyS_sendmsg) from [<c000fa00>] (ret_fast_syscall+0x0/0x48)
	console [ttyUSB0] enabled

Fixes: 36697529b5bb ("tty: Replace ldisc locking with ldisc_sem")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 1 additions and 0 deletions Inline Diff

drivers/usb/serial/console.c
Diff comments   View file @ 68d91b4
1 /* 1 /*
2 * USB Serial Console driver 2 * USB Serial Console driver
3 * 3 *
4 * Copyright (C) 2001 - 2002 Greg Kroah-Hartman (greg@kroah.com) 4 * Copyright (C) 2001 - 2002 Greg Kroah-Hartman (greg@kroah.com)
5 * 5 *
6 * This program is free software; you can redistribute it and/or 6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License version 7 * modify it under the terms of the GNU General Public License version
8 * 2 as published by the Free Software Foundation. 8 * 2 as published by the Free Software Foundation.
9 * 9 *
10 * Thanks to Randy Dunlap for the original version of this code. 10 * Thanks to Randy Dunlap for the original version of this code.
11 * 11 *
12 */ 12 */
13 13
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 15
16 #include <linux/kernel.h> 16 #include <linux/kernel.h>
17 #include <linux/slab.h> 17 #include <linux/slab.h>
18 #include <linux/tty.h> 18 #include <linux/tty.h>
19 #include <linux/console.h> 19 #include <linux/console.h>
20 #include <linux/serial.h> 20 #include <linux/serial.h>
21 #include <linux/usb.h> 21 #include <linux/usb.h>
22 #include <linux/usb/serial.h> 22 #include <linux/usb/serial.h>
23 23
24 struct usbcons_info { 24 struct usbcons_info {
25 int magic; 25 int magic;
26 int break_flag; 26 int break_flag;
27 struct usb_serial_port *port; 27 struct usb_serial_port *port;
28 }; 28 };
29 29
30 static struct usbcons_info usbcons_info; 30 static struct usbcons_info usbcons_info;
31 static struct console usbcons; 31 static struct console usbcons;
32 32
33 /* 33 /*
34 * ------------------------------------------------------------ 34 * ------------------------------------------------------------
35 * USB Serial console driver 35 * USB Serial console driver
36 * 36 *
37 * Much of the code here is copied from drivers/char/serial.c 37 * Much of the code here is copied from drivers/char/serial.c
38 * and implements a phony serial console in the same way that 38 * and implements a phony serial console in the same way that
39 * serial.c does so that in case some software queries it, 39 * serial.c does so that in case some software queries it,
40 * it will get the same results. 40 * it will get the same results.
41 * 41 *
42 * Things that are different from the way the serial port code 42 * Things that are different from the way the serial port code
43 * does things, is that we call the lower level usb-serial 43 * does things, is that we call the lower level usb-serial
44 * driver code to initialize the device, and we set the initial 44 * driver code to initialize the device, and we set the initial
45 * console speeds based on the command line arguments. 45 * console speeds based on the command line arguments.
46 * ------------------------------------------------------------ 46 * ------------------------------------------------------------
47 */ 47 */
48 48
49 49
50 /* 50 /*
51 * The parsing of the command line works exactly like the 51 * The parsing of the command line works exactly like the
52 * serial.c code, except that the specifier is "ttyUSB" instead 52 * serial.c code, except that the specifier is "ttyUSB" instead
53 * of "ttyS". 53 * of "ttyS".
54 */ 54 */
55 static int usb_console_setup(struct console *co, char *options) 55 static int usb_console_setup(struct console *co, char *options)
56 { 56 {
57 struct usbcons_info *info = &usbcons_info; 57 struct usbcons_info *info = &usbcons_info;
58 int baud = 9600; 58 int baud = 9600;
59 int bits = 8; 59 int bits = 8;
60 int parity = 'n'; 60 int parity = 'n';
61 int doflow = 0; 61 int doflow = 0;
62 int cflag = CREAD | HUPCL | CLOCAL; 62 int cflag = CREAD | HUPCL | CLOCAL;
63 char *s; 63 char *s;
64 struct usb_serial *serial; 64 struct usb_serial *serial;
65 struct usb_serial_port *port; 65 struct usb_serial_port *port;
66 int retval; 66 int retval;
67 struct tty_struct *tty = NULL; 67 struct tty_struct *tty = NULL;
68 struct ktermios dummy; 68 struct ktermios dummy;
69 69
70 if (options) { 70 if (options) {
71 baud = simple_strtoul(options, NULL, 10); 71 baud = simple_strtoul(options, NULL, 10);
72 s = options; 72 s = options;
73 while (*s >= '0' && *s <= '9') 73 while (*s >= '0' && *s <= '9')
74 s++; 74 s++;
75 if (*s) 75 if (*s)
76 parity = *s++; 76 parity = *s++;
77 if (*s) 77 if (*s)
78 bits = *s++ - '0'; 78 bits = *s++ - '0';
79 if (*s) 79 if (*s)
80 doflow = (*s++ == 'r'); 80 doflow = (*s++ == 'r');
81 } 81 }
82 82
83 /* Sane default */ 83 /* Sane default */
84 if (baud == 0) 84 if (baud == 0)
85 baud = 9600; 85 baud = 9600;
86 86
87 switch (bits) { 87 switch (bits) {
88 case 7: 88 case 7:
89 cflag |= CS7; 89 cflag |= CS7;
90 break; 90 break;
91 default: 91 default:
92 case 8: 92 case 8:
93 cflag |= CS8; 93 cflag |= CS8;
94 break; 94 break;
95 } 95 }
96 switch (parity) { 96 switch (parity) {
97 case 'o': case 'O': 97 case 'o': case 'O':
98 cflag |= PARODD; 98 cflag |= PARODD;
99 break; 99 break;
100 case 'e': case 'E': 100 case 'e': case 'E':
101 cflag |= PARENB; 101 cflag |= PARENB;
102 break; 102 break;
103 } 103 }
104 co->cflag = cflag; 104 co->cflag = cflag;
105 105
106 /* 106 /*
107 * no need to check the index here: if the index is wrong, console 107 * no need to check the index here: if the index is wrong, console
108 * code won't call us 108 * code won't call us
109 */ 109 */
110 port = usb_serial_port_get_by_minor(co->index); 110 port = usb_serial_port_get_by_minor(co->index);
111 if (port == NULL) { 111 if (port == NULL) {
112 /* no device is connected yet, sorry :( */ 112 /* no device is connected yet, sorry :( */
113 pr_err("No USB device connected to ttyUSB%i\n", co->index); 113 pr_err("No USB device connected to ttyUSB%i\n", co->index);
114 return -ENODEV; 114 return -ENODEV;
115 } 115 }
116 serial = port->serial; 116 serial = port->serial;
117 117
118 retval = usb_autopm_get_interface(serial->interface); 118 retval = usb_autopm_get_interface(serial->interface);
119 if (retval) 119 if (retval)
120 goto error_get_interface; 120 goto error_get_interface;
121 121
122 tty_port_tty_set(&port->port, NULL); 122 tty_port_tty_set(&port->port, NULL);
123 123
124 info->port = port; 124 info->port = port;
125 125
126 ++port->port.count; 126 ++port->port.count;
127 if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) { 127 if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {
128 if (serial->type->set_termios) { 128 if (serial->type->set_termios) {
129 /* 129 /*
130 * allocate a fake tty so the driver can initialize 130 * allocate a fake tty so the driver can initialize
131 * the termios structure, then later call set_termios to 131 * the termios structure, then later call set_termios to
132 * configure according to command line arguments 132 * configure according to command line arguments
133 */ 133 */
134 tty = kzalloc(sizeof(*tty), GFP_KERNEL); 134 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
135 if (!tty) { 135 if (!tty) {
136 retval = -ENOMEM; 136 retval = -ENOMEM;
137 goto reset_open_count; 137 goto reset_open_count;
138 } 138 }
139 kref_init(&tty->kref); 139 kref_init(&tty->kref);
140 tty_port_tty_set(&port->port, tty); 140 tty_port_tty_set(&port->port, tty);
141 tty->driver = usb_serial_tty_driver; 141 tty->driver = usb_serial_tty_driver;
142 tty->index = co->index; 142 tty->index = co->index;
143 init_ldsem(&tty->ldisc_sem);
143 if (tty_init_termios(tty)) { 144 if (tty_init_termios(tty)) {
144 retval = -ENOMEM; 145 retval = -ENOMEM;
145 goto free_tty; 146 goto free_tty;
146 } 147 }
147 } 148 }
148 149
149 /* only call the device specific open if this 150 /* only call the device specific open if this
150 * is the first time the port is opened */ 151 * is the first time the port is opened */
151 retval = serial->type->open(NULL, port); 152 retval = serial->type->open(NULL, port);
152 if (retval) { 153 if (retval) {
153 dev_err(&port->dev, "could not open USB console port\n"); 154 dev_err(&port->dev, "could not open USB console port\n");
154 goto fail; 155 goto fail;
155 } 156 }
156 157
157 if (serial->type->set_termios) { 158 if (serial->type->set_termios) {
158 tty->termios.c_cflag = cflag; 159 tty->termios.c_cflag = cflag;
159 tty_termios_encode_baud_rate(&tty->termios, baud, baud); 160 tty_termios_encode_baud_rate(&tty->termios, baud, baud);
160 memset(&dummy, 0, sizeof(struct ktermios)); 161 memset(&dummy, 0, sizeof(struct ktermios));
161 serial->type->set_termios(tty, port, &dummy); 162 serial->type->set_termios(tty, port, &dummy);
162 163
163 tty_port_tty_set(&port->port, NULL); 164 tty_port_tty_set(&port->port, NULL);
164 kfree(tty); 165 kfree(tty);
165 } 166 }
166 set_bit(ASYNCB_INITIALIZED, &port->port.flags); 167 set_bit(ASYNCB_INITIALIZED, &port->port.flags);
167 } 168 }
168 /* Now that any required fake tty operations are completed restore 169 /* Now that any required fake tty operations are completed restore
169 * the tty port count */ 170 * the tty port count */
170 --port->port.count; 171 --port->port.count;
171 /* The console is special in terms of closing the device so 172 /* The console is special in terms of closing the device so
172 * indicate this port is now acting as a system console. */ 173 * indicate this port is now acting as a system console. */
173 port->port.console = 1; 174 port->port.console = 1;
174 175
175 mutex_unlock(&serial->disc_mutex); 176 mutex_unlock(&serial->disc_mutex);
176 return retval; 177 return retval;
177 178
178 fail: 179 fail:
179 tty_port_tty_set(&port->port, NULL); 180 tty_port_tty_set(&port->port, NULL);
180 free_tty: 181 free_tty:
181 kfree(tty); 182 kfree(tty);
182 reset_open_count: 183 reset_open_count:
183 port->port.count = 0; 184 port->port.count = 0;
184 usb_autopm_put_interface(serial->interface); 185 usb_autopm_put_interface(serial->interface);
185 error_get_interface: 186 error_get_interface:
186 usb_serial_put(serial); 187 usb_serial_put(serial);
187 mutex_unlock(&serial->disc_mutex); 188 mutex_unlock(&serial->disc_mutex);
188 return retval; 189 return retval;
189 } 190 }
190 191
191 static void usb_console_write(struct console *co, 192 static void usb_console_write(struct console *co,
192 const char *buf, unsigned count) 193 const char *buf, unsigned count)
193 { 194 {
194 static struct usbcons_info *info = &usbcons_info; 195 static struct usbcons_info *info = &usbcons_info;
195 struct usb_serial_port *port = info->port; 196 struct usb_serial_port *port = info->port;
196 struct usb_serial *serial; 197 struct usb_serial *serial;
197 int retval = -ENODEV; 198 int retval = -ENODEV;
198 199
199 if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED) 200 if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
200 return; 201 return;
201 serial = port->serial; 202 serial = port->serial;
202 203
203 if (count == 0) 204 if (count == 0)
204 return; 205 return;
205 206
206 dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count); 207 dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);
207 208
208 if (!port->port.console) { 209 if (!port->port.console) {
209 dev_dbg(&port->dev, "%s - port not opened\n", __func__); 210 dev_dbg(&port->dev, "%s - port not opened\n", __func__);
210 return; 211 return;
211 } 212 }
212 213
213 while (count) { 214 while (count) {
214 unsigned int i; 215 unsigned int i;
215 unsigned int lf; 216 unsigned int lf;
216 /* search for LF so we can insert CR if necessary */ 217 /* search for LF so we can insert CR if necessary */
217 for (i = 0, lf = 0 ; i < count ; i++) { 218 for (i = 0, lf = 0 ; i < count ; i++) {
218 if (*(buf + i) == 10) { 219 if (*(buf + i) == 10) {
219 lf = 1; 220 lf = 1;
220 i++; 221 i++;
221 break; 222 break;
222 } 223 }
223 } 224 }
224 /* pass on to the driver specific version of this function if 225 /* pass on to the driver specific version of this function if
225 it is available */ 226 it is available */
226 retval = serial->type->write(NULL, port, buf, i); 227 retval = serial->type->write(NULL, port, buf, i);
227 dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval); 228 dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval);
228 if (lf) { 229 if (lf) {
229 /* append CR after LF */ 230 /* append CR after LF */
230 unsigned char cr = 13; 231 unsigned char cr = 13;
231 retval = serial->type->write(NULL, port, &cr, 1); 232 retval = serial->type->write(NULL, port, &cr, 1);
232 dev_dbg(&port->dev, "%s - write cr: %d\n", 233 dev_dbg(&port->dev, "%s - write cr: %d\n",
233 __func__, retval); 234 __func__, retval);
234 } 235 }
235 buf += i; 236 buf += i;
236 count -= i; 237 count -= i;
237 } 238 }
238 } 239 }
239 240
240 static struct tty_driver *usb_console_device(struct console *co, int *index) 241 static struct tty_driver *usb_console_device(struct console *co, int *index)
241 { 242 {
242 struct tty_driver **p = (struct tty_driver **)co->data; 243 struct tty_driver **p = (struct tty_driver **)co->data;
243 244
244 if (!*p) 245 if (!*p)
245 return NULL; 246 return NULL;
246 247
247 *index = co->index; 248 *index = co->index;
248 return *p; 249 return *p;
249 } 250 }
250 251
251 static struct console usbcons = { 252 static struct console usbcons = {
252 .name = "ttyUSB", 253 .name = "ttyUSB",
253 .write = usb_console_write, 254 .write = usb_console_write,
254 .device = usb_console_device, 255 .device = usb_console_device,
255 .setup = usb_console_setup, 256 .setup = usb_console_setup,
256 .flags = CON_PRINTBUFFER, 257 .flags = CON_PRINTBUFFER,
257 .index = -1, 258 .index = -1,
258 .data = &usb_serial_tty_driver, 259 .data = &usb_serial_tty_driver,
259 }; 260 };
260 261
261 void usb_serial_console_disconnect(struct usb_serial *serial) 262 void usb_serial_console_disconnect(struct usb_serial *serial)
262 { 263 {
263 if (serial && serial->port && serial->port[0] 264 if (serial && serial->port && serial->port[0]
264 && serial->port[0] == usbcons_info.port) { 265 && serial->port[0] == usbcons_info.port) {
265 usb_serial_console_exit(); 266 usb_serial_console_exit();
266 usb_serial_put(serial); 267 usb_serial_put(serial);
267 } 268 }
268 } 269 }
269 270
270 void usb_serial_console_init(int minor) 271 void usb_serial_console_init(int minor)
271 { 272 {
272 if (minor == 0) { 273 if (minor == 0) {
273 /* 274 /*
274 * Call register_console() if this is the first device plugged 275 * Call register_console() if this is the first device plugged
275 * in. If we call it earlier, then the callback to 276 * in. If we call it earlier, then the callback to
276 * console_setup() will fail, as there is not a device seen by 277 * console_setup() will fail, as there is not a device seen by
277 * the USB subsystem yet. 278 * the USB subsystem yet.
278 */ 279 */
279 /* 280 /*
280 * Register console. 281 * Register console.
281 * NOTES: 282 * NOTES:
282 * console_setup() is called (back) immediately (from 283 * console_setup() is called (back) immediately (from
283 * register_console). console_write() is called immediately 284 * register_console). console_write() is called immediately
284 * from register_console iff CON_PRINTBUFFER is set in flags. 285 * from register_console iff CON_PRINTBUFFER is set in flags.
285 */ 286 */
286 pr_debug("registering the USB serial console.\n"); 287 pr_debug("registering the USB serial console.\n");
287 register_console(&usbcons); 288 register_console(&usbcons);
288 } 289 }
289 } 290 }
290 291
291 void usb_serial_console_exit(void) 292 void usb_serial_console_exit(void)
292 { 293 {
293 if (usbcons_info.port) { 294 if (usbcons_info.port) {
294 unregister_console(&usbcons); 295 unregister_console(&usbcons);
295 usbcons_info.port->port.console = 0; 296 usbcons_info.port->port.console = 0;
296 usbcons_info.port = NULL; 297 usbcons_info.port = NULL;
297 } 298 }
298 } 299 }
299 300
300 301