[PATCH] sysctl_{,ms_}jiffies: fix oldlen semantics
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> --- kernel/sysctl.c | 44 ++++++++++++++++++++++++++++---------------- 1 file changed, 28 insertions(+), 16 deletions(-) --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2752,17 +2752,23 @@ int sysctl_jiffies(ctl_table *table, int void __user *oldval, size_t __user *oldlenp, void __user *newval, size_t newlen, void **context) { - if (oldval) { + if (oldval && oldlenp) { size_t olen; - if (oldlenp) { - if (get_user(olen, oldlenp)) + + if (get_user(olen, oldlenp)) + return -EFAULT; + if (olen) { + int val; + + if (olen < sizeof(int)) + return -EINVAL; + + val = *(int *)(table->data) / HZ; + if (put_user(val, (int __user *)oldval)) + return -EFAULT; + if (put_user(sizeof(int), oldlenp)) return -EFAULT; - if (olen!=sizeof(int)) - return -EINVAL; } - if (put_user(*(int *)(table->data)/HZ, (int __user *)oldval) || - (oldlenp && put_user(sizeof(int),oldlenp))) - return -EFAULT; } if (newval && newlen) { int new; @@ -2780,17 +2786,23 @@ int sysctl_ms_jiffies(ctl_table *table, void __user *oldval, size_t __user *oldlenp, void __user *newval, size_t newlen, void **context) { - if (oldval) { + if (oldval && oldlenp) { size_t olen; - if (oldlenp) { - if (get_user(olen, oldlenp)) + + if (get_user(olen, oldlenp)) + return -EFAULT; + if (olen) { + int val; + + if (olen < sizeof(int)) + return -EINVAL; + + 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 (olen!=sizeof(int)) - return -EINVAL; } - if (put_user(jiffies_to_msecs(*(int *)(table->data)), (int __user *)oldval) || - (oldlenp && put_user(sizeof(int),oldlenp))) - return -EFAULT; } if (newval && newlen) { int new;