On Tue, Oct 2, 2012 at 10:12 PM, David Rientjes <rientjes@xxxxxxxxxx> wrote: > On Tue, 2 Oct 2012, Kees Cook wrote: > >> In the paranoid case of sysctl kernel.kptr_restrict=2, mask the kernel >> virtual addresses in /proc/vmallocinfo too. >> >> Reported-by: Brad Spengler <spender@xxxxxxxxxxxxxx> >> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > /proc/vmallocinfo is S_IRUSR, not S_IRUGO, so exactly what are you trying > to protect? Trying to block the root user from seeing virtual memory addresses (mode 2 of kptr_restrict). Documentation/sysctl/kernel.txt: "This toggle indicates whether restrictions are placed on exposing kernel addresses via /proc and other interfaces. When kptr_restrict is set to (0), there are no restrictions. When kptr_restrict is set to (1), the default, kernel pointers printed using the %pK format specifier will be replaced with 0's unless the user has CAP_SYSLOG. When kptr_restrict is set to (2), kernel pointers printed using %pK will be replaced with 0's regardless of privileges." Even though it's S_IRUSR, it still needs %pK for the paranoid case. -Kees -- Kees Cook Chrome OS Security -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>