s390/compat: correct restore of high gprs on signal return

git commit 8070361799ae1e3f4ef347bd10f0a508ac10acfb
"s390: add support for vector extension"
broke 31-bit compat processes in regard to signal handling.

The restore_sigregs_ext32() function is used to restore the additional
elements from the user space signal frame. Among the additional elements
are the upper registers halves for 64-bit register support for 31-bit
processes. The copy_from_user that is used to retrieve the high-gprs
array from the user stack uses an incorrect length, 8 bytes instead of
64 bytes. This causes incorrect upper register halves to get loaded.

Cc: stable@vger.kernel.org # 3.8+
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/compat_signal.c b/arch/s390/kernel/compat_signal.c
index 66c94417c0ba09a471244a629c78d2457f38b17d..4af60374eba01fba89dc8b170a41428b094160b5 100644 (file)
--- a/arch/s390/kernel/compat_signal.c
+++ b/arch/s390/kernel/compat_signal.c
@@ -271,7 +271,7 @@ static int restore_sigregs_ext32(struct pt_regs *regs,
 
        /* Restore high gprs from signal stack */
        if (__copy_from_user(&gprs_high, &sregs_ext->gprs_high,
-                            sizeof(&sregs_ext->gprs_high)))
+                            sizeof(sregs_ext->gprs_high)))
                return -EFAULT;
        for (i = 0; i < NUM_GPRS; i++)
                *(__u32 *)&regs->gprs[i] = gprs_high[i];