[PATCH 3.12 037/155] console: Fix console name size mismatch

[Jiri Slaby]

From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 30a22c215a0007603ffc08021f2e8b64018517dd upstream.

commit 6ae9200f2cab7 ("enlarge console.name") increased the storage
for the console name to 16 bytes, but not the corresponding
struct console_cmdline::name storage. Console names longer than
8 bytes cause read beyond end-of-string and failure to match
console; I'm not sure if there are other unexpected consequences.

Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 kernel/printk/console_cmdline.h | 2 +-
 kernel/printk/printk.c          | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/printk/console_cmdline.h b/kernel/printk/console_cmdline.h
index cbd69d842341..2ca4a8b5fe57 100644
--- a/kernel/printk/console_cmdline.h
+++ b/kernel/printk/console_cmdline.h
@@ -3,7 +3,7 @@
 
 struct console_cmdline
 {
-	char	name[8];			/* Name of the driver	    */
+	char	name[16];			/* Name of the driver	    */
 	int	index;				/* Minor dev. to use	    */
 	char	*options;			/* Options for the driver   */
 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 0f9149036885..fbafa885eee1 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2281,6 +2281,7 @@ void register_console(struct console *newcon)
 	for (i = 0, c = console_cmdline;
 	     i < MAX_CMDLINECONSOLES && c->name[0];
 	     i++, c++) {
+		BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
 		if (strcmp(c->name, newcon->name) != 0)
 			continue;
 		if (newcon->index >= 0 &&
-- 
2.3.4

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