Re: [PATCH][RESEND] mm: Fix off-by-one bug in print_nodes_state
From: KOSAKI Motohiro <hidden>
Date: 2011-12-18 21:28:45
Also in:
lkml
(12/18/11 6:58 AM), Ryota Ozaki wrote:
quoted hunk ↗ jump to hunk
/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. Signed-off-by: Ryota Ozaki<redacted> --- 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]);
PAGE_SIZE-1. This seems another off by one. buf[n++] = '¥n' mean override old trailing '¥0' and buf[n] = '¥0' mean to append one byte. Then totally, we append one byte.
+ buf[n++] = '\n'; + buf[n] = '\0'; return n; }
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