[PATCH 4.4 37/93] printk: fix parsing of "brl=" option

From: Greg Kroah-Hartman
Date: Thu Oct 06 2016 - 05:01:06 EST


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

------------------

From: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>

commit ae6c33ba6e37eea3012fe2640b22400ef3f2d0f3 upstream.

Commit bbeddf52adc1 ("printk: move braille console support into separate
braille.[ch] files") moved the parsing of braille-related options into
_braille_console_setup(), changing the type of variable str from char*
to char**. In this commit, memcmp(str, "brl,", 4) was correctly updated
to memcmp(*str, "brl,", 4) but not memcmp(str, "brl=", 4).

Update the code to make "brl=" option work again and replace memcmp()
with strncmp() to make the compiler able to detect such an issue.

Fixes: bbeddf52adc1 ("printk: move braille console support into separate braille.[ch] files")
Link: http://lkml.kernel.org/r/20160823165700.28952-1-nicolas.iooss_linux@xxxxxxx
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
kernel/printk/braille.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/printk/braille.c
+++ b/kernel/printk/braille.c
@@ -9,10 +9,10 @@

char *_braille_console_setup(char **str, char **brl_options)
{
- if (!memcmp(*str, "brl,", 4)) {
+ if (!strncmp(*str, "brl,", 4)) {
*brl_options = "";
*str += 4;
- } else if (!memcmp(str, "brl=", 4)) {
+ } else if (!strncmp(*str, "brl=", 4)) {
*brl_options = *str + 4;
*str = strchr(*brl_options, ',');
if (!*str)