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From:   Ross Philipson <ross.philipson@oracle.com>
To:     linux-kernel@vger.kernel.org, x86@kernel.org
Cc:     ross.philipson@oracle.com, dpsmith@apertussolutions.com,
        tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
        luto@amacapital.net, dave.hansen@linux.intel.com,
        kanth.ghatraju@oracle.com, trenchboot-devel@googlegroups.com
Subject: [PATCH 1/2] x86: Check return values from early_memremap calls
Date:   Fri, 15 Apr 2022 11:10:00 -0400
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There are a number of places where early_memremap 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@oracle.com>
---
 arch/x86/kernel/devicetree.c | 10 ++++++++++
 arch/x86/kernel/e820.c       |  5 +++++
 arch/x86/kernel/jailhouse.c  |  6 ++++++
 arch/x86/kernel/mpparse.c    | 23 +++++++++++++++++++++++
 arch/x86/kernel/setup.c      |  5 +++++
 arch/x86/xen/enlighten_hvm.c |  2 ++
 arch/x86/xen/mmu_pv.c        |  8 ++++++++
 arch/x86/xen/setup.c         |  2 ++
 8 files changed, 61 insertions(+)

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index 5cd51f2..ca23875 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -292,10 +292,20 @@ static void __init x86_flattree_get_config(void)
 	map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK), (u64)128);
 
 	dt = early_memremap(initial_dtb, map_len);
+	if (!dt) {
+		pr_warn("devicetree: failed to memremap initial dtb\n");
+		return;
+	}
+
 	size = fdt_totalsize(dt);
 	if (map_len < size) {
 		early_memunmap(dt, map_len);
 		dt = early_memremap(initial_dtb, size);
+		if (!dt) {
+			pr_warn("devicetree: failed to memremap initial dtb\n");
+			return;
+		}
+
 		map_len = size;
 	}
 
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index f267205..f90b883 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -728,6 +728,11 @@ void __init e820__memory_setup_extended(u64 phys_addr, u32 data_len)
 	struct setup_data *sdata;
 
 	sdata = early_memremap(phys_addr, data_len);
+	if (!sdata) {
+		pr_warn("e820: failed to memremap extended\n");
+		return;
+	}
+
 	entries = sdata->len / sizeof(*extmap);
 	extmap = (struct boot_e820_entry *)(sdata->data);
 
diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
index 4eb8f2d..80db0c2 100644
--- a/arch/x86/kernel/jailhouse.c
+++ b/arch/x86/kernel/jailhouse.c
@@ -221,6 +221,9 @@ static void __init jailhouse_init_platform(void)
 
 	while (pa_data) {
 		mapping = early_memremap(pa_data, sizeof(header));
+		if (!mapping)
+			panic("Jailhouse: failed to memremap setup_data header\n");
+
 		memcpy(&header, mapping, sizeof(header));
 		early_memunmap(mapping, sizeof(header));
 
@@ -241,6 +244,9 @@ static void __init jailhouse_init_platform(void)
 	setup_data_len = min_t(unsigned long, sizeof(setup_data),
 			       (unsigned long)header.len);
 	mapping = early_memremap(pa_data, setup_data_len);
+	if (!mapping)
+		panic("Jailhouse: failed to memremap setup_data\n");
+
 	memcpy(&setup_data, mapping, setup_data_len);
 	early_memunmap(mapping, setup_data_len);
 
diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c
index fed721f..8bac042 100644
--- a/arch/x86/kernel/mpparse.c
+++ b/arch/x86/kernel/mpparse.c
@@ -424,6 +424,9 @@ static unsigned long __init get_mpc_size(unsigned long physptr)
 	unsigned long size;
 
 	mpc = early_memremap(physptr, PAGE_SIZE);
+	if (!mpc)
+		return 0;
+
 	size = mpc->length;
 	early_memunmap(mpc, PAGE_SIZE);
 	apic_printk(APIC_VERBOSE, "  mpc: %lx-%lx\n", physptr, physptr + size);
@@ -437,7 +440,16 @@ static int __init check_physptr(struct mpf_intel *mpf, unsigned int early)
 	unsigned long size;
 
 	size = get_mpc_size(mpf->physptr);
+	if (!size) {
+		pr_err("MPTABLE: error getting MP table size\n");
+		return -1;
+	}
+
 	mpc = early_memremap(mpf->physptr, size);
+	if (!mpc) {
+		pr_err("MPTABLE: error mapping MP table physptr\n");
+		return -1;
+	}
 
 	/*
 	 * Read the physical hardware table.  Anything here will
@@ -552,6 +564,7 @@ void __init default_get_smp_config(unsigned int early)
 
 static void __init smp_reserve_memory(struct mpf_intel *mpf)
 {
+	/* If get_mpc_size() is 0, memblock_reserve() will just do nothing */
 	memblock_reserve(mpf->physptr, get_mpc_size(mpf->physptr));
 }
 
@@ -567,6 +580,11 @@ static int __init smp_scan_config(unsigned long base, unsigned long length)
 
 	while (length > 0) {
 		bp = early_memremap(base, length);
+		if (!bp) {
+			pr_err("MPTABLE: error mapping SMP config\n");
+			return 0;
+		}
+
 		mpf = (struct mpf_intel *)bp;
 		if ((*bp == SMP_MAGIC_IDENT) &&
 		    (mpf->length == 1) &&
@@ -864,6 +882,11 @@ static int __init update_mp_table(void)
 		goto do_unmap_mpf;
 
 	size = get_mpc_size(mpf->physptr);
+	if (!size) {
+		pr_err("MPTABLE: error getting MP table size\n");
+		goto do_unmap_mpf;
+	}
+
 	mpc = early_memremap(mpf->physptr, size);
 	if (!mpc) {
 		pr_err("MPTABLE: mpc early_memremap() failed\n");
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index c95b9ac..824e901 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -345,6 +345,11 @@ static void __init parse_setup_data(void)
 		u32 data_len, data_type;
 
 		data = early_memremap(pa_data, sizeof(*data));
+		if (!data) {
+			pr_warn("setup: failed to memremap in parse_setup_data\n");
+			return;
+		}
+
 		data_len = data->len + sizeof(struct setup_data);
 		data_type = data->type;
 		pa_next = data->next;
diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 517a9d8..6182c5b 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -64,6 +64,8 @@ static void __init reserve_shared_info(void)
 
 	memblock_reserve(pa, PAGE_SIZE);
 	HYPERVISOR_shared_info = early_memremap(pa, PAGE_SIZE);
+	if (!HYPERVISOR_shared_info)
+		panic("xen: failed to memmap hypervisor shared page: 0x%llx\n", pa);
 }
 
 static void __init xen_hvm_init_mem_mapping(void)
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 0035486..2aff5c6 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1823,6 +1823,8 @@ static unsigned long __init xen_read_phys_ulong(phys_addr_t addr)
 	unsigned long val;
 
 	vaddr = early_memremap_ro(addr, sizeof(val));
+	if (!vaddr)
+		panic("xen: failed to memmap physical address: 0x%llx\n", addr);
 	val = *vaddr;
 	early_memunmap(vaddr, sizeof(val));
 	return val;
@@ -1918,14 +1920,20 @@ void __init xen_relocate_p2m(void)
 	new_p2m = (unsigned long *)(2 * PGDIR_SIZE);
 	for (idx_pud = 0; idx_pud < n_pud; idx_pud++) {
 		pud = early_memremap(pud_phys, PAGE_SIZE);
+		if (!pud)
+			panic("xen: failed to memmap PUD physical address: 0x%llx\n", pud_phys);
 		clear_page(pud);
 		for (idx_pmd = 0; idx_pmd < min(n_pmd, PTRS_PER_PUD);
 				idx_pmd++) {
 			pmd = early_memremap(pmd_phys, PAGE_SIZE);
+			if (!pmd)
+				panic("xen: failed to memmap PMD physical address: 0x%llx\n", pmd_phys);
 			clear_page(pmd);
 			for (idx_pt = 0; idx_pt < min(n_pt, PTRS_PER_PMD);
 					idx_pt++) {
 				pt = early_memremap(pt_phys, PAGE_SIZE);
+				if (!pt)
+					panic("xen: failed to memmap PT physical address: 0x%llx\n", pt_phys);
 				clear_page(pt);
 				for (idx_pte = 0;
 				     idx_pte < min(n_pte, PTRS_PER_PTE);
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 81aa46f..5e74496 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -685,6 +685,8 @@ static void __init xen_phys_memcpy(phys_addr_t dest, phys_addr_t src,
 		len = min(dest_len, src_len);
 		to = early_memremap(dest - dest_off, dest_len + dest_off);
 		from = early_memremap(src - src_off, src_len + src_off);
+		if (!to || !from)
+			panic("xen: failed to memmap for physical address memcpy\n");
 		memcpy(to, from, len);
 		early_memunmap(to, dest_len + dest_off);
 		early_memunmap(from, src_len + src_off);
-- 
1.8.3.1