Allowing users to write to address space provides mechanisms that may permit modification of the kernel at runtime. Prevent this if securelevel has been set.
Signed-off-by: Matthew Garrett <matthew.garr...@nebula.com> --- drivers/char/mem.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 741f536..91d1cff 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -159,6 +159,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, unsigned long copied; void *ptr; + if (get_securelevel() > 0) + return -EPERM; + if (!valid_phys_addr_range(p, count)) return -EFAULT; @@ -497,6 +500,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (get_securelevel() > 0) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p); -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html