From 333e71cfe2b3ca30ed1fb2d28510c542feb8379d Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky <schwidefsky@de.ibm.com> Date: Mon, 27 Jun 2016 17:06:45 +0200 Subject: [PATCH] s390: fix test_fp_ctl inline assembly contraints commit bcf4dd5f9ee096bd1510f838dd4750c35df4e38b upstream. The test_fp_ctl function is used to test if a given value is a valid floating-point control. The inline assembly in test_fp_ctl uses an incorrect constraint for the 'orig_fpc' variable. If the compiler chooses the same register for 'fpc' and 'orig_fpc' the test_fp_ctl() function always returns true. This allows user space to trigger kernel oopses with invalid floating-point control values on the signal stack. This problem has been introduced with git commit 4725c86055f5bbdcdf "s390: fix save and restore of the floating-point-control register" Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/s390/include/asm/fpu/api.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/include/asm/fpu/api.h b/arch/s390/include/asm/fpu/api.h index 5e04f3cbd320..8ae236b0f80b 100644 --- a/arch/s390/include/asm/fpu/api.h +++ b/arch/s390/include/asm/fpu/api.h @@ -22,7 +22,7 @@ static inline int test_fp_ctl(u32 fpc) " la %0,0\n" "1:\n" EX_TABLE(0b,1b) - : "=d" (rc), "=d" (orig_fpc) + : "=d" (rc), "=&d" (orig_fpc) : "d" (fpc), "0" (-EINVAL)); return rc; } -- 2.34.1