linux-kernel - [PATCHv2] of: Check for phys_addr_t overflows in early_init_dt_add_memory

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Date:	Thu, 19 Jun 2014 20:13:38 -0700
From:	Laura Abbott <lauraa@...eaurora.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robherring2@...il.com>
Cc:	Laura Abbott <lauraa@...eaurora.org>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Nicolas Pitre <nicolas.pitre@...aro.org>
Subject: [PATCHv2] of: Check for phys_addr_t overflows in early_init_dt_add_memory_arch

The common early_init_dt_add_memory_arch takes the base and size
of a memory region as u64 types. The function never checks if
the base and size can actually fit in a phys_addr_t which may
be smaller than 64-bits. This may result in incorrect memory
being passed to memblock_add if the memory falls outside the
range of phys_addr_t. Add range checks for the base and size if
phys_addr_t is smaller than u64.

Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Signed-off-by: Laura Abbott <lauraa@...eaurora.org>
---
v2: Switched to sizeof(phys_addr_t) < sizeof(u64) instead of macros.
Sending to right e-mails/mailing lists this time.

 drivers/of/fdt.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index c4cddf0..b777d8f 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -880,6 +880,21 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
 	const u64 phys_offset = __pa(PAGE_OFFSET);
 	base &= PAGE_MASK;
 	size &= PAGE_MASK;
+
+	if (sizeof(phys_addr_t) < sizeof(u64)) {
+		if (base > ULONG_MAX) {
+			pr_warning("Ignoring memory block 0x%llx - 0x%llx\n",
+					base, base + size);
+			return;
+		}
+
+		if (base + size > ULONG_MAX) {
+			pr_warning("Ignoring memory range 0x%lx - 0x%llx\n",
+					ULONG_MAX, base + size);
+			size = ULONG_MAX - base;
+		}
+	}
+
 	if (base + size < phys_offset) {
 		pr_warning("Ignoring memory block 0x%llx - 0x%llx\n",
 			   base, base + size);
-- 
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