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
