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

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Date:   Fri, 15 Apr 2022 11:10:01 -0400
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
Subject: [PATCH 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.

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 f5a48e6..7a64287 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 68b3892..35b228d 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 & 0xfffffff0, 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