* Re: [PATCH] mm: Fix off-by-one bug in print_nodes_state
2011-11-26 15:42 [PATCH] mm: Fix off-by-one bug in print_nodes_state Ryota Ozaki
@ 2012-04-20 20:05 ` Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2012-04-20 20:05 UTC (permalink / raw)
To: Ryota Ozaki; +Cc: linux-mm, stable
On Sun, 27 Nov 2011 00:42:53 +0900
Ryota Ozaki <ozaki.ryota@gmail.com> wrote:
> /sys/devices/system/node/{online,possible} involve a garbage byte
> because print_nodes_state returns content size + 1. To fix the bug,
> the patch changes the use of cpuset_sprintf_cpulist to follow the
> use at other places, which is clearer and safer.
>
> This bug was introduced since v2.6.24 (bde631a51876f23e9).
>
> Signed-off-by: Ryota Ozaki <ozaki.ryota@gmail.com>
> ---
> drivers/base/node.c | 8 +++-----
> 1 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 5693ece..ef7c1f9 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -587,11 +587,9 @@ static ssize_t print_nodes_state(enum node_states state, char *buf)
> {
> int n;
>
> - n = nodelist_scnprintf(buf, PAGE_SIZE, node_states[state]);
> - if (n > 0 && PAGE_SIZE > n + 1) {
> - *(buf + n++) = '\n';
> - *(buf + n++) = '\0';
> - }
> + n = nodelist_scnprintf(buf, PAGE_SIZE-2, node_states[state]);
> + buf[n++] = '\n';
> + buf[n] = '\0';
> return n;
> }
The patch looks good, thanks.
I have issues with the lib/bitmap.c documentation, btw. Could someone
please double-check this?
From: Andrew Morton <akpm@linux-foundation.org>
Subject: lib/bitmap.c: fix documentation for scnprintf() functions
The code comments for bscnl_emit() and bitmap_scnlistprintf() are
describing snprintf() return semantics, but these functions use
scnprintf() return semantics. Fix that, and document the
bitmap_scnprintf() return value as well.
Cc: Ryota Ozaki <ozaki.ryota@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
lib/bitmap.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff -puN lib/bitmap.c~a lib/bitmap.c
--- a/lib/bitmap.c~a
+++ a/lib/bitmap.c
@@ -369,7 +369,8 @@ EXPORT_SYMBOL(bitmap_find_next_zero_area
* @nmaskbits: size of bitmap, in bits
*
* Exactly @nmaskbits bits are displayed. Hex digits are grouped into
- * comma-separated sets of eight digits per set.
+ * comma-separated sets of eight digits per set. Returns the number of
+ * characters which were written to *buf, excluding the trailing \0.
*/
int bitmap_scnprintf(char *buf, unsigned int buflen,
const unsigned long *maskp, int nmaskbits)
@@ -517,8 +518,8 @@ EXPORT_SYMBOL(bitmap_parse_user);
*
* Helper routine for bitmap_scnlistprintf(). Write decimal number
* or range to buf, suppressing output past buf+buflen, with optional
- * comma-prefix. Return len of what would be written to buf, if it
- * all fit.
+ * comma-prefix. Return len of what was written to *buf, excluding the
+ * trailing \0.
*/
static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
{
@@ -544,9 +545,8 @@ static inline int bscnl_emit(char *buf,
* the range. Output format is compatible with the format
* accepted as input by bitmap_parselist().
*
- * The return value is the number of characters which would be
- * generated for the given input, excluding the trailing '\0', as
- * per ISO C99.
+ * The return value is the number of characters which were written to *buf
+ * excluding the trailing '\0', as per ISO C99's scnprintf.
*/
int bitmap_scnlistprintf(char *buf, unsigned int buflen,
const unsigned long *maskp, int nmaskbits)
_
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