Prevent out-of-range access if the returned SCLP SCCB response is smaller in size than the address of the Secure-IPL flag.

Fixes: c9896acc7851 ("s390/ipl: Provide has_secure sysfs attribute") Cc: stable@vger.kernel.org # 5.2+ Signed-off-by: Alexander Egorenkov egorenar@linux.ibm.com --- drivers/s390/char/sclp_early.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/char/sclp_early.c b/drivers/s390/char/sclp_early.c index 2f3515fa242a..f3d5c7f4c13d 100644 --- a/drivers/s390/char/sclp_early.c +++ b/drivers/s390/char/sclp_early.c @@ -45,13 +45,14 @@ static void __init sclp_early_facilities_detect(void) sclp.has_gisaf = !!(sccb->fac118 & 0x08); sclp.has_hvs = !!(sccb->fac119 & 0x80); sclp.has_kss = !!(sccb->fac98 & 0x01); - sclp.has_sipl = !!(sccb->cbl & 0x4000); if (sccb->fac85 & 0x02) S390_lowcore.machine_flags |= MACHINE_FLAG_ESOP; if (sccb->fac91 & 0x40) S390_lowcore.machine_flags |= MACHINE_FLAG_TLB_GUEST; if (sccb->cpuoff > 134) sclp.has_diag318 = !!(sccb->byte_134 & 0x80); + if (sccb->cpuoff > 137) + sclp.has_sipl = !!(sccb->cbl & 0x4000); sclp.rnmax = sccb->rnmax ? sccb->rnmax : sccb->rnmax2; sclp.rzm = sccb->rnsize ? sccb->rnsize : sccb->rnsize2; sclp.rzm <<= 20;