s390/sclp: fix Secure-IPL facility detection

PATCH New Alexander Egorenkov 1 participant 1 message Sep 9, 2021

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Stable branch s390

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Alexander Egorenkov

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2021-09-09 10:53 UTC #0 lore raw

PATCH 1/1 s390/sclp: fix Secure-IPL facility detection

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 [email protected] # 5.2+

Signed-off-by Alexander Egorenkov <[email protected]>

---
 drivers/s390/char/sclp_early.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

drivers/s390/char/sclp_early.c +2 -1

index 2f3515fa242a..f3d5c7f4c13d 100644
@@ -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;

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2.31.1