Le 13/07/2021 à 07:31, Christopher M. Riedl a écrit :
Code patching on powerpc with a STRICT_KERNEL_RWX uses a userspace
address in a temporary mm on Radix now. Use __put_user() to avoid write
failures due to KUAP when attempting a "hijack" on the patching address.
__put_user() also works with the non-userspace, vmalloc-based patching
address on non-Radix MMUs.
It is not really clean to use __put_user() on non user address, allthought it
works by change.
I think it would be better to do something like
if (is_kernel_addr(addr))
copy_to_kernel_nofault(...);
else
copy_to_user_nofault(...);
Signed-off-by: Christopher M. Riedl <c...@linux.ibm.com>
---
drivers/misc/lkdtm/perms.c | 9 ---------
1 file changed, 9 deletions(-)
diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
index 41e87e5f9cc86..da6a34a0a49fb 100644
--- a/drivers/misc/lkdtm/perms.c
+++ b/drivers/misc/lkdtm/perms.c
@@ -262,16 +262,7 @@ static inline u32 lkdtm_read_patch_site(void)
/* Returns True if the write succeeds */
static inline bool lkdtm_try_write(u32 data, u32 *addr)
{
-#ifdef CONFIG_PPC
- __put_kernel_nofault(addr, &data, u32, err);
- return true;
-
-err:
- return false;
-#endif
-#ifdef CONFIG_X86_64
return !__put_user(data, addr);
-#endif
}
static int lkdtm_patching_cpu(void *data)
