Messages in this thread | | | Date | Sun, 18 Dec 2011 16:28:40 -0500 | From | KOSAKI Motohiro <> | Subject | Re: [PATCH][RESEND] mm: Fix off-by-one bug in print_nodes_state |
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(12/18/11 6:58 AM), Ryota Ozaki 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. > > 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]);
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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