4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Oberparleiter <oberpar@xxxxxxxxxxxxxxxxxx>
commit 77759137248f34864a8f7a58bbcebfcf1047504a upstream.
Prevent kernel crashes due to unhandled exceptions raised by the CHSC
instruction which may for example be triggered by invalid ioctl data.
Fixes: 64150adf89df ("s390/cio: Introduce generic synchronous CHSC IOCTL")
Signed-off-by: Peter Oberparleiter <oberpar@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/s390/cio/ioasm.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/drivers/s390/cio/ioasm.c
+++ b/drivers/s390/cio/ioasm.c
@@ -165,13 +165,15 @@ int tpi(struct tpi_info *addr)
int chsc(void *chsc_area)
{
typedef struct { char _[4096]; } addr_type;
- int cc;
+ int cc = -EIO;
asm volatile(
" .insn rre,0xb25f0000,%2,0\n"
- " ipm %0\n"
+ "0: ipm %0\n"
" srl %0,28\n"
- : "=d" (cc), "=m" (*(addr_type *) chsc_area)
+ "1:\n"
+ EX_TABLE(0b, 1b)
+ : "+d" (cc), "=m" (*(addr_type *) chsc_area)
: "d" (chsc_area), "m" (*(addr_type *) chsc_area)
: "cc");
trace_s390_cio_chsc(chsc_area, cc);