RUNTIME_USER_COPY_CHECK restricts copy_*_user() to deny stack and slab
buffer overflows. However, it is redundant for copying memory via
/dev/mem and /dev/kmem. With STRICT_DEVMEM=n it should be possible to
copy any kernel memory without the checks. So, use unchecked versions
of copy_*_user().
Include <linux/uaccess-check.h> is needed for architectures not yet
implementing DEBUG_RUNTIME_USER_COPY_CHECKS.
v3 - Simplified addition of new architectures.
Signed-off-by: Vasiliy Kulikov <segoon@xxxxxxxxxxxx>
---
drivers/char/mem.c | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 8fc04b4..39e4aba 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -26,6 +26,7 @@
#include <linux/bootmem.h>
#include <linux/splice.h>
#include <linux/pfn.h>
+#include <linux/uaccess-check.h>
#include <asm/uaccess.h>
#include <asm/io.h>
@@ -132,7 +133,7 @@ static ssize_t read_mem(struct file *file, char __user *buf,
if (!ptr)
return -EFAULT;
- remaining = copy_to_user(buf, ptr, sz);
+ remaining = copy_to_user_unchecked(buf, ptr, sz);
unxlate_dev_mem_ptr(p, ptr);
if (remaining)
return -EFAULT;
@@ -190,7 +191,7 @@ static ssize_t write_mem(struct file *file, const char __user *buf,
return -EFAULT;
}
- copied = copy_from_user(ptr, buf, sz);
+ copied = copy_from_user_unchecked(ptr, buf, sz);
unxlate_dev_mem_ptr(p, ptr);
if (copied) {
written += sz - copied;
@@ -428,7 +429,7 @@ static ssize_t read_kmem(struct file *file, char __user *buf,
*/
kbuf = xlate_dev_kmem_ptr((char *)p);
- if (copy_to_user(buf, kbuf, sz))
+ if (copy_to_user_unchecked(buf, kbuf, sz))
return -EFAULT;
buf += sz;
p += sz;
@@ -498,7 +499,7 @@ static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
*/
ptr = xlate_dev_kmem_ptr((char *)p);
- copied = copy_from_user(ptr, buf, sz);
+ copied = copy_from_user_unchecked(ptr, buf, sz);
if (copied) {
written += sz - copied;
if (written)
--
--
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