linux-kernel - [PATCH v2 2/2] x86: Check return values from early

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Date:   Thu, 10 Nov 2022 15:45:21 +0000
From:   Ross Philipson <ross.philipson@...cle.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     ross.philipson@...cle.com, dpsmith@...rtussolutions.com,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        luto@...capital.net, dave.hansen@...ux.intel.com,
        kanth.ghatraju@...cle.com, trenchboot-devel@...glegroups.com,
        jailhouse-dev@...glegroups.com, jan.kiszka@...mens.com,
        xen-devel@...ts.xenproject.org, jgross@...e.com,
        boris.ostrovsky@...cle.com, andrew.cooper3@...rix.com
Subject: [PATCH v2 2/2] x86: Check return values from early_ioremap calls

There are a number of places where early_ioremap is called
but the return pointer is not checked for NULL. The call
can result in a NULL being returned so the checks must
be added.

On allocation failures, panic() was used since this seemed
to be the action taken on other failures in the modules
touched by this patch.

Signed-off-by: Ross Philipson <ross.philipson@...cle.com>
---
 arch/x86/kernel/apic/x2apic_uv_x.c | 2 ++
 arch/x86/kernel/early_printk.c     | 2 ++
 arch/x86/kernel/vsmp_64.c          | 3 +++
 3 files changed, 7 insertions(+)

diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index 4828552..4ffdc27 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -75,6 +75,8 @@ static unsigned long __init uv_early_read_mmr(unsigned long addr)
 	unsigned long val, *mmr;
 
 	mmr = early_ioremap(UV_LOCAL_MMR_BASE | addr, sizeof(*mmr));
+	if (!mmr)
+		panic("UV: error: failed to ioremap MMR\n");
 	val = *mmr;
 	early_iounmap(mmr, sizeof(*mmr));
 
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 44f9370..1fe590d 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -290,6 +290,8 @@ static __init void early_pci_serial_init(char *s)
 		/* WARNING! assuming the address is always in the first 4G */
 		early_serial_base =
 			(unsigned long)early_ioremap(bar0 & PCI_BASE_ADDRESS_MEM_MASK, 0x10);
+		if (!early_serial_base)
+			panic("early_serial: failed to ioremap MMIO BAR\n");
 		write_pci_config(bus, slot, func, PCI_COMMAND,
 				 cmdreg|PCI_COMMAND_MEMORY);
 	}
diff --git a/arch/x86/kernel/vsmp_64.c b/arch/x86/kernel/vsmp_64.c
index 796cfaa..39769f4 100644
--- a/arch/x86/kernel/vsmp_64.c
+++ b/arch/x86/kernel/vsmp_64.c
@@ -32,6 +32,9 @@ static void __init set_vsmp_ctl(void)
 	/* set vSMP magic bits to indicate vSMP capable kernel */
 	cfg = read_pci_config(0, 0x1f, 0, PCI_BASE_ADDRESS_0);
 	address = early_ioremap(cfg, 8);
+	if (WARN_ON(!address))
+		return;
+
 	cap = readl(address);
 	ctl = readl(address + 4);
 	printk(KERN_INFO "vSMP CTL: capabilities:0x%08x  control:0x%08x\n",
-- 
1.8.3.1