From: Zev Weiss zev@bewilderbeest.net Subject: kernel/sysctl.c: add missing range check in do_proc_dointvec_minmax_conv

This bug has apparently existed since the introduction of this function in the pre-git era (4500e91754d3 in Thomas Gleixner's history.git, "[NET]: Add proc_dointvec_userhz_jiffies, use it for proper handling of neighbour sysctls."). As a minimal fix we can simply duplicate the corresponding check in do_proc_dointvec_conv().

Link: http://lkml.kernel.org/r/20190207123426.9202-3-zev@bewilderbeest.net Signed-off-by: Zev Weiss zev@bewilderbeest.net Cc: Brendan Higgins brendanhiggins@google.com Cc: Iurii Zaikin yzaikin@google.com Cc: Kees Cook keescook@chromium.org Cc: Luis Chamberlain mcgrof@kernel.org Cc: stable@vger.kernel.org [2.6.2+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

--- a/kernel/sysctl.c~kernel-sysctlc-add-missing-range-check-in-do_proc_dointvec_minmax_conv +++ a/kernel/sysctl.c @@ -2645,7 +2645,16 @@ static int do_proc_dointvec_minmax_conv( { struct do_proc_dointvec_minmax_conv_param *param = data; if (write) { - int val = *negp ? -*lvalp : *lvalp; + int val; + if (*negp) { + if (*lvalp > (unsigned long) INT_MAX + 1) + return -EINVAL; + val = -*lvalp; + } else { + if (*lvalp > (unsigned long) INT_MAX) + return -EINVAL; + val = *lvalp; + } if ((param->min && *param->min > val) || (param->max && *param->max < val)) return -EINVAL; _