From: Matthew Garrett Date: Fri, 9 Mar 2012 13:39:37 +0000 (-0500) Subject: acpi: Limit access to custom_method if securelevel is set X-Git-Tag: archive/raspbian/4.9.82-1+deb9u3+rpi1_jessie~8^2~45 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=c12e9d112441c6b36bb3e019d202908e24d124d7;p=linux-4.9.git acpi: Limit access to custom_method if securelevel is set custom_method effectively allows arbitrary access to system memory, making it possible for an attacker to modify the kernel at runtime. Prevent this if securelevel has been set. Signed-off-by: Matthew Garrett Gbp-Pq: Topic features/all/securelevel Gbp-Pq: Name acpi-limit-access-to-custom_method-if-securelevel-is.patch --- diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index c68e72414a67..359f45d54543 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -8,6 +8,7 @@ #include #include #include +#include #include "internal.h" @@ -29,6 +30,9 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, struct acpi_table_header table; acpi_status status; + if (get_securelevel() > 0) + return -EPERM; + if (!(*ppos)) { /* parse the table header to get the table length */ if (count <= sizeof(struct acpi_table_header))