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authorLinus Torvalds <torvalds@linux-foundation.org>2017-09-07 21:00:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-07 21:00:52 -0700
commitcef5d0f952a03d42051141742632078d488b0c6b (patch)
tree29b27c96f9f297b2cf84612a0dbb8dcc11ffa4d6 /kernel
parent0fb02e718f5fd88b175387bc2a9313b27609f0da (diff)
parent077a1cc06f72f95efd077d433993c16191008e47 (diff)
downloadlinux-cef5d0f952a03d42051141742632078d488b0c6b.tar.bz2
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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/printk/printk.c69
1 files changed, 32 insertions, 37 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 97bda7b0655b..512f7c2baedd 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -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)
{
@@ -2659,16 +2647,23 @@ 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)))
- unregister_console(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);
}
}
ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL,