Commit 41e19926 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390: workaround invalid gcc-11 out of bounds read warning 



GCC 11.1.0 and 11.2.0 generate a wrong warning when compiling the
kernel e.g. with allmodconfig:

arch/s390/kernel/setup.c: In function ‘setup_lowcore_dat_on’:
./include/linux/fortify-string.h:57:33: error: ‘__builtin_memcpy’ reading 128 bytes from a region of size 0 [-Werror=stringop-overread]
...
arch/s390/kernel/setup.c:526:9: note: in expansion of macro ‘memcpy’
  526 |         memcpy(abs_lc->cregs_save_area, S390_lowcore.cregs_save_area,
      |         ^~~~~~

This could be addressed by using absolute_pointer() with the
S390_lowcore macro, but this is not a good idea since this generates
worse code for performance critical paths.

Therefore simply use a for loop to copy the array in question and get
rid of the warning.

Reported-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 1ecf7bd9

arch/s390/kernel/setup.c

+3 −2
Original line number Diff line number Diff line
@@ -508,6 +508,7 @@ static void __init setup_lowcore_dat_on(void) 
{

	struct lowcore *abs_lc;

	unsigned long flags;

	int i;



	__ctl_clear_bit(0, 28);

	S390_lowcore.external_new_psw.mask |= PSW_MASK_DAT;
@@ -523,8 +524,8 @@ static void __init setup_lowcore_dat_on(void) 
	abs_lc = get_abs_lowcore(&flags);

	abs_lc->restart_flags = RESTART_FLAG_CTLREGS;

	abs_lc->program_new_psw = S390_lowcore.program_new_psw;

	memcpy(abs_lc->cregs_save_area, S390_lowcore.cregs_save_area,

	       sizeof(abs_lc->cregs_save_area));

	for (i = 0; i < 16; i++)

		abs_lc->cregs_save_area[i] = S390_lowcore.cregs_save_area[i];

	put_abs_lowcore(abs_lc, flags);

}