linux-kernel - [PATCH 3.16 14/72] ARM: zynq: Use memcpy_toio instead of memcpy on smp bring-up

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Message-ID: <lsq.1575813165.3329877@decadent.org.uk>
Date:   Sun, 08 Dec 2019 13:52:58 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Luis Araneda" <luaraneda@...il.com>,
        "Michal Simek" <michal.simek@...inx.com>
Subject: [PATCH 3.16 14/72] ARM: zynq: Use memcpy_toio instead of memcpy
 on smp bring-up

3.16.79-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Luis Araneda <luaraneda@...il.com>

commit b7005d4ef4f3aa2dc24019ffba03a322557ac43d upstream.

This fixes a kernel panic on memcpy when
FORTIFY_SOURCE is enabled.

The initial smp implementation on commit aa7eb2bb4e4a
("arm: zynq: Add smp support")
used memcpy, which worked fine until commit ee333554fed5
("ARM: 8749/1: Kconfig: Add ARCH_HAS_FORTIFY_SOURCE")
enabled overflow checks at runtime, producing a read
overflow panic.

The computed size of memcpy args are:
- p_size (dst): 4294967295 = (size_t) -1
- q_size (src): 1
- size (len): 8

Additionally, the memory is marked as __iomem, so one of
the memcpy_* functions should be used for read/write.

Fixes: aa7eb2bb4e4a ("arm: zynq: Add smp support")
Signed-off-by: Luis Araneda <luaraneda@...il.com>
Signed-off-by: Michal Simek <michal.simek@...inx.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/arm/mach-zynq/platsmp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm/mach-zynq/platsmp.c
+++ b/arch/arm/mach-zynq/platsmp.c
@@ -65,7 +65,7 @@ int zynq_cpun_start(u32 address, int cpu
 			* 0x4: Jump by mov instruction
 			* 0x8: Jumping address
 			*/
-			memcpy((__force void *)zero, &zynq_secondary_trampoline,
+			memcpy_toio(zero, &zynq_secondary_trampoline,
 							trampoline_size);
 			writel(address, zero + trampoline_size);