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Commit cef5d0f9 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk 

Pull printk updates from Petr Mladek:

 - Do not allow use of freed init data and code even when boot consoles
   are forced to stay. Also check for the init memory more precisely.

 - Some code clean up by starting contributors.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
  printk: Clean up do_syslog() error handling
  printk/console: Enhance the check for consoles using init memory
  printk/console: Always disable boot consoles that use init memory before it is freed
  printk: Modify operators of printed_len and text_len
parents 0fb02e71 077a1cc0

kernel/printk/printk.c

+32 −37
Original line number Diff line number Diff line
@@ -1434,7 +1434,7 @@ int do_syslog(int type, char __user *buf, int len, int source) 


	error = check_syslog_permissions(type, source);

	if (error)

		goto out;

		return error;



	switch (type) {

	case SYSLOG_ACTION_CLOSE:	/* Close log */
@@ -1442,20 +1442,16 @@ int do_syslog(int type, char __user *buf, int len, int source) 
	case SYSLOG_ACTION_OPEN:	/* Open log */

		break;

	case SYSLOG_ACTION_READ:	/* Read from log */

		error = -EINVAL;

		if (!buf || len < 0)

			goto out;

		error = 0;

			return -EINVAL;

		if (!len)

			goto out;

		if (!access_ok(VERIFY_WRITE, buf, len)) {

			error = -EFAULT;

			goto out;

		}

			return 0;

		if (!access_ok(VERIFY_WRITE, buf, len))

			return -EFAULT;

		error = wait_event_interruptible(log_wait,

						 syslog_seq != log_next_seq);

		if (error)

			goto out;

			return error;

		error = syslog_print(buf, len);

		break;

	/* Read/clear last kernel messages */
@@ -1464,16 +1460,12 @@ int do_syslog(int type, char __user *buf, int len, int source) 
		/* FALL THRU */

	/* Read last kernel messages */

	case SYSLOG_ACTION_READ_ALL:

		error = -EINVAL;

		if (!buf || len < 0)

			goto out;

		error = 0;

			return -EINVAL;

		if (!len)

			goto out;

		if (!access_ok(VERIFY_WRITE, buf, len)) {

			error = -EFAULT;

			goto out;

		}

			return 0;

		if (!access_ok(VERIFY_WRITE, buf, len))

			return -EFAULT;

		error = syslog_print_all(buf, len, clear);

		break;

	/* Clear ring buffer */
@@ -1495,15 +1487,13 @@ int do_syslog(int type, char __user *buf, int len, int source) 
		break;

	/* Set level of messages printed to console */

	case SYSLOG_ACTION_CONSOLE_LEVEL:

		error = -EINVAL;

		if (len < 1 || len > 8)

			goto out;

			return -EINVAL;

		if (len < minimum_console_loglevel)

			len = minimum_console_loglevel;

		console_loglevel = len;

		/* Implicitly re-enable logging to console */

		saved_console_loglevel = LOGLEVEL_DEFAULT;

		error = 0;

		break;

	/* Number of chars in the log buffer */

	case SYSLOG_ACTION_SIZE_UNREAD:
@@ -1525,7 +1515,6 @@ int do_syslog(int type, char __user *buf, int len, int source) 
			u64 seq = syslog_seq;

			u32 idx = syslog_idx;



			error = 0;

			while (seq < log_next_seq) {

				struct printk_log *msg = log_from_idx(idx);
@@ -1545,7 +1534,7 @@ int do_syslog(int type, char __user *buf, int len, int source) 
		error = -EINVAL;

		break;

	}

out:



	return error;

}
@@ -1697,10 +1686,10 @@ asmlinkage int vprintk_emit(int facility, int level, 
{

	static char textbuf[LOG_LINE_MAX];

	char *text = textbuf;

	size_t text_len = 0;

	size_t text_len;

	enum log_flags lflags = 0;

	unsigned long flags;

	int printed_len = 0;

	int printed_len;

	bool in_sched = false;



	if (level == LOGLEVEL_SCHED) {
@@ -1753,7 +1742,7 @@ asmlinkage int vprintk_emit(int facility, int level, 
	if (dict)

		lflags |= LOG_PREFIX|LOG_NEWLINE;



	printed_len += log_output(facility, level, lflags, dict, dictlen, text, text_len);

	printed_len = log_output(facility, level, lflags, dict, dictlen, text, text_len);



	logbuf_unlock_irqrestore(flags);
@@ -2649,9 +2638,8 @@ void __init console_init(void) 
 * makes it difficult to diagnose problems that occur during this time.

 *

 * To mitigate this problem somewhat, only unregister consoles whose memory

 * intersects with the init section. Note that code exists elsewhere to get

 * rid of the boot console as soon as the proper console shows up, so there

 * won't be side-effects from postponing the removal.

 * intersects with the init section. Note that all other boot consoles will

 * get unregistred when the real preferred console is registered.

 */

static int __init printk_late_init(void)

{
@@ -2659,15 +2647,22 @@ static int __init printk_late_init(void) 
	int ret;



	for_each_console(con) {

		if (!keep_bootcon && con->flags & CON_BOOT) {

		if (!(con->flags & CON_BOOT))

			continue;



		/* Check addresses that might be used for enabled consoles. */

		if (init_section_intersects(con, sizeof(*con)) ||

		    init_section_contains(con->write, 0) ||

		    init_section_contains(con->read, 0) ||

		    init_section_contains(con->device, 0) ||

		    init_section_contains(con->unblank, 0) ||

		    init_section_contains(con->data, 0)) {

			/*

			 * Make sure to unregister boot consoles whose data

			 * resides in the init section before the init section

			 * is discarded. Boot consoles whose data will stick

			 * around will automatically be unregistered when the

			 * proper console replaces them.

			 * Please, consider moving the reported consoles out

			 * of the init section.

			 */

			if (init_section_intersects(con, sizeof(*con)))

			pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n",

				con->name, con->index);

			unregister_console(con);

		}

	}