Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1353391

[RFC 3/7] leds: avoid fragile sprintf use

Show all headers | View raw

Passing overlapping src and dst buffers to sprintf is fragile (and
undefined behaviour). So while this may seem like a clever way of
appending a newline and obtaining the length of the resulting string
at the same time, we might as well use that pbuf points to the current
end of string and do the same thing with an assignment, increment and
pointer subtraction.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/leds/led-class-flash.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/led-class-flash.c b/drivers/leds/led-class-flash.c
index cf398275a53c..4fae548a7822 100644
--- a/drivers/leds/led-class-flash.c
+++ b/drivers/leds/led-class-flash.c
@@ -212,7 +212,8 @@ static ssize_t flash_fault_show(struct device *dev,
 		mask <<= 1;
 	}
 
-	return sprintf(buf, "%s\n", buf);
+	*pbuf++ = '\n';
+	return pbuf - buf;
 }
 static DEVICE_ATTR_RO(flash_fault);
 
-- 
2.1.4

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[RFC 0/7] eliminate snprintf with overlapping src and dst Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-03-08 21:50 +0100
  [RFC 5/7] wlcore: avoid fragile snprintf use Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-03-08 21:50 +0100
    Re: [RFC 5/7] wlcore: avoid fragile snprintf use Kalle Valo <kvalo@codeaurora.org> - 2016-03-09 12:50 +0100
  [RFC 3/7] leds: avoid fragile sprintf use Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-03-08 21:50 +0100
  [RFC 4/7] drivers/media/pci/zoran: avoid fragile snprintf use Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-03-08 21:50 +0100
  [RFC 2/7] Input: joystick - avoid fragile snprintf use Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-03-08 21:50 +0100
    Re: [RFC 2/7] Input: joystick - avoid fragile snprintf use Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-03-09 07:50 +0100
  [RFC 1/7] drm/amdkfd: avoid fragile and inefficient snprintf use Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-03-08 21:50 +0100
    Re: [RFC 1/7] drm/amdkfd: avoid fragile and inefficient snprintf use Oded Gabbay <oded.gabbay@gmail.com> - 2016-03-14 15:40 +0100
      Re: [RFC 1/7] drm/amdkfd: avoid fragile and inefficient snprintf use Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-03-14 20:20 +0100
  Re: [RFC 0/7] eliminate snprintf with overlapping src and dst Kees Cook <keescook@chromium.org> - 2016-03-09 00:10 +0100
  Re: [RFC 0/7] eliminate snprintf with overlapping src and dst Kees Cook <keescook@chromium.org> - 2016-03-09 00:20 +0100
  Re: [RFC 0/7] eliminate snprintf with overlapping src and dst Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-03-09 08:00 +0100
  Re: [RFC 0/7] eliminate snprintf with overlapping src and dst Andrew Morton <akpm@linux-foundation.org> - 2016-03-09 21:50 +0100
    Re: [RFC 0/7] eliminate snprintf with overlapping src and dst Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-03-09 23:20 +0100
    Re: [RFC 0/7] eliminate snprintf with overlapping src and dst One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-03-10 15:10 +0100

csiph-web