[PATCH] sysctl_{,ms_}jiffies: fix oldlen semantics (3ee75ac3) · Commits · 戴 / test

currently it's 1) if *oldlenp == 0, don't writeback anything 2) if *oldlenp >= table->maxlen, don't writeback more than table->maxlen bytes and rewrite *oldlenp don't look at underlying type granularity 3) if 0 < *oldlenp < table->maxlen, *cough* string sysctls don't writeback more than *oldlenp bytes. OK, that's because sizeof(char) == 1 int sysctls writeback anything in (0, table->maxlen] range Though accept integers divisible by sizeof(int) for writing. sysctl_jiffies and sysctl_ms_jiffies don't writeback anything but sizeof(int), which violates 1) and 2). So, make sysctl_jiffies and sysctl_ms_jiffies accept a) *oldlenp == 0, not doing writeback b) *oldlenp >= sizeof(int), writing one integer. -EINVAL still returned for *oldlenp == 1, 2, 3. Signed-off-by:

Alexey Dobriyan <adobriyan@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

kernel/sysctl.c

+28 −16

Original line number	Diff line number	Diff line
		@@ -2553,17 +2553,23 @@ int sysctl_jiffies(ctl_table table, int __user name, int nlen,
		void __user oldval, size_t __user oldlenp,
		void __user *newval, size_t newlen)
		{
		if (oldval) {
		if (oldval && oldlenp) {
		size_t olen;
		if (oldlenp) {

		if (get_user(olen, oldlenp))
		return -EFAULT;
		if (olen!=sizeof(int))
		if (olen) {
		int val;

		if (olen < sizeof(int))
		return -EINVAL;
		}
		if (put_user((int )(table->data)/HZ, (int __user *)oldval) \|\|
		(oldlenp && put_user(sizeof(int),oldlenp)))

		val = (int )(table->data) / HZ;
		if (put_user(val, (int __user *)oldval))
		return -EFAULT;
		if (put_user(sizeof(int), oldlenp))
		return -EFAULT;
		}
		}
		if (newval && newlen) {
		int new;
		@@ -2581,17 +2587,23 @@ int sysctl_ms_jiffies(ctl_table table, int __user name, int nlen,
		void __user oldval, size_t __user oldlenp,
		void __user *newval, size_t newlen)
		{
		if (oldval) {
		if (oldval && oldlenp) {
		size_t olen;
		if (oldlenp) {

		if (get_user(olen, oldlenp))
		return -EFAULT;
		if (olen!=sizeof(int))
		if (olen) {
		int val;

		if (olen < sizeof(int))
		return -EINVAL;
		}
		if (put_user(jiffies_to_msecs((int )(table->data)), (int __user *)oldval) \|\|
		(oldlenp && put_user(sizeof(int),oldlenp)))

		val = jiffies_to_msecs((int )(table->data));
		if (put_user(val, (int __user *)oldval))
		return -EFAULT;
		if (put_user(sizeof(int), oldlenp))
		return -EFAULT;
		}
		}
		if (newval && newlen) {
		int new;

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