Thread (14 messages) 14 messages, 5 authors, 2012-12-03

Re: [patch v2] x86, UV: integer wrap bug in uv_hub_ipi_value()

From: walter harms <hidden>
Date: 2012-12-02 15:34:05
Also in: lkml


Am 02.12.2012 11:44, schrieb Dan Carpenter:
quoted hunk ↗ jump to hunk
This is a static checker fix.  The problem is that we store the bits
from "uv_apicid_hibits" into "apicid" (the high 16 bits) but then we
shift it 16 bit to the left.  "apicid" is an int so it wraps and we lose
them.

Signed-off-by: Dan Carpenter <redacted>
---
v2: Style fix.  Don't use ulong.

I don't have this hardware so I can't test it.  There may also be other
bugs which this patch does not addressed.  These files are only compiled
on x86_64 and "unsigned long" is used throughout to mean 64 bits.
diff --git a/arch/x86/include/asm/uv/uv_hub.h b/arch/x86/include/asm/uv/uv_hub.h
index 21f7385..e7a83d5 100644
--- a/arch/x86/include/asm/uv/uv_hub.h
+++ b/arch/x86/include/asm/uv/uv_hub.h
@@ -577,7 +577,7 @@ static unsigned long uv_hub_ipi_value(int apicid, int vector, int mode)
 {
 	apicid |= uv_apicid_hibits;
 	return (1UL << UVH_IPI_INT_SEND_SHFT) |
-			((apicid) << UVH_IPI_INT_APIC_ID_SHFT) |
+			((unsigned long)apicid << UVH_IPI_INT_APIC_ID_SHFT) |
 			(mode << UVH_IPI_INT_DELIVERY_MODE_SHFT) |
 			(vector << UVH_IPI_INT_VECTOR_SHFT);
 }
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index 8cfade9..6d93b2f 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -194,13 +194,13 @@ static int __cpuinit uv_wakeup_secondary(int phys_apicid, unsigned long start_ri
 	pnode = uv_apicid_to_pnode(phys_apicid);
 	phys_apicid |= uv_apicid_hibits;
 	val = (1UL << UVH_IPI_INT_SEND_SHFT) |
-	    (phys_apicid << UVH_IPI_INT_APIC_ID_SHFT) |
+	    ((unsigned long)phys_apicid << UVH_IPI_INT_APIC_ID_SHFT) |
 	    ((start_rip << UVH_IPI_INT_VECTOR_SHFT) >> 12) |
 	    APIC_DM_INIT;
 	uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
 
 	val = (1UL << UVH_IPI_INT_SEND_SHFT) |
-	    (phys_apicid << UVH_IPI_INT_APIC_ID_SHFT) |
+	    ((unsigned long)phys_apicid << UVH_IPI_INT_APIC_ID_SHFT) |
 	    ((start_rip << UVH_IPI_INT_VECTOR_SHFT) >> 12) |
 	    APIC_DM_STARTUP;
 	uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
making this more readable is hard but what is about:

val=(1UL << UVH_IPI_INT_SEND_SHFT) |
     ((unsigned long)phys_apicid << UVH_IPI_INT_APIC_ID_SHFT) |
      ((start_rip << UVH_IPI_INT_VECTOR_SHFT) >> 12);

 uv_write_global_mmr64(pnode, UVH_IPI_INT, val|APIC_DM_INIT);

 uv_write_global_mmr64(pnode, UVH_IPI_INT, val|APIC_DM_STARTUP);


just my 2 cents,
 re
  wh
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