When copy from user fails due to a machine check on poison reading
user data it should return an error code.
---
Separate patch just now, but likely needs to be combined with patches
to iteration code for bisection safety.
---
arch/x86/lib/copy_user_64.S | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index 77b9b2a3b5c8..2987118c541a 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -14,6 +14,7 @@
#include <asm/alternative-asm.h>
#include <asm/asm.h>
#include <asm/smap.h>
+#include <asm/errno.h>
#include <asm/export.h>
#include <asm/trapnr.h>
@@ -237,18 +238,21 @@ SYM_CODE_START_LOCAL(.Lcopy_user_handle_tail)
cmp $X86_TRAP_MC,%eax /* check if X86_TRAP_MC */
je 3f
1: rep movsb
-2: mov %ecx,%eax
+ mov %ecx,%eax
+ ASM_CLAC
+ ret
+
+2:
+ cmp $X86_TRAP_MC,%eax
+ je 3f
+ mov %ecx,%eax
ASM_CLAC
ret
/*
- * Return zero to pretend that this copy succeeded. This
- * is counter-intuitive, but needed to prevent the code
- * in lib/iov_iter.c from retrying and running back into
- * the poison cache line again. The machine check handler
- * will ensure that a SIGBUS is sent to the task.
+ * Return -EFAULT for the machine check cases
*/
-3: xorl %eax,%eax
+3: movl $-EFAULT,%eax
ASM_CLAC
ret
--
2.29.2
