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Date: Fri, 21 Jul 2017 08:39:04 +0800 (CST) From: "Tiezhu Yang" <kernelpatch@....com> To: gregkh@...uxfoundation.org Cc: linux-kernel@...r.kernel.org Subject: [PATCH] driver core: restrict buffer length in online_store() According to Documentation/ABI/testing/sysfs-devices-online, in order to control CPU N's hotplug state, we should write one of 'Yy1Nn0' to the file /sys/devices/system/cpu/cpuN/online, other values should be invalid. so the buffer length should be 2, buf[0] is one of 'Yy1Nn0' and buf[1] is '\n'. without patch: [root@...alhost home]# echo 0test > /sys/devices/system/cpu/cpu1/online [root@...alhost home]# cat /sys/devices/system/cpu/cpu1/online 0 [root@...alhost home]# echo 1test > /sys/devices/system/cpu/cpu1/online [root@...alhost home]# cat /sys/devices/system/cpu/cpu1/online 1 [root@...alhost home]# echo ntest > /sys/devices/system/cpu/cpu1/online [root@...alhost home]# cat /sys/devices/system/cpu/cpu1/online 0 [root@...alhost home]# echo ytest > /sys/devices/system/cpu/cpu1/online [root@...alhost home]# cat /sys/devices/system/cpu/cpu1/online 1 [root@...alhost home]# echo Ntest > /sys/devices/system/cpu/cpu1/online [root@...alhost home]# cat /sys/devices/system/cpu/cpu1/online 0 [root@...alhost home]# echo Ytest > /sys/devices/system/cpu/cpu1/online [root@...alhost home]# cat /sys/devices/system/cpu/cpu1/online 1 with patch: [root@...alhost home]# echo 0test > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Invalid argument [root@...alhost home]# echo 1test > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Invalid argument [root@...alhost home]# echo ntest > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Invalid argument [root@...alhost home]# echo ytest > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Invalid argument [root@...alhost home]# echo Ntest > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Invalid argument [root@...alhost home]# echo Ytest > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Invalid argument Signed-off-by: Tiezhu Yang <kernelpatch@....com> --- drivers/base/core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/base/core.c b/drivers/base/core.c index 755451f..6588ed5 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1005,6 +1005,12 @@ static ssize_t online_store(struct device *dev, struct device_attribute *attr, bool val; int ret; + /* According to Documentation/ABI/testing/sysfs-devices-online, + * the buf length should be 2, buf[0]: one of 'Yy1Nn0', buf[1]: '\n'. + */ + if (strlen(buf) != 2) + return -EINVAL; + ret = strtobool(buf, &val); if (ret < 0) return ret; -- 1.8.3.1
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