linux-kernel - [PATCH 4.2.y-ckt 047/211] tpm, tpm_crb: fix unaligned read of the command buffer address

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Message-Id: <1452023119-25647-48-git-send-email-kamal@canonical.com>
Date:	Tue,  5 Jan 2016 11:42:35 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	Peter Huewe <peterhuewe@....de>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 047/211] tpm, tpm_crb: fix unaligned read of the command buffer address

4.2.8-ckt1 -stable review patch.  If anyone has any objections, please let me know.

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

From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

commit 149789ce9d472e6b4fd99336e779ab843754a96c upstream.

The command buffer address must be read with exactly two 32-bit reads.
Otherwise, on some HW platforms, it seems that HW will abort the read
operation, which causes CPU to fill the read bytes with 1's. Therefore,
we cannot rely on memcpy_fromio() but must call ioread32() two times
instead.

Also, this matches the PC Client Platform TPM Profile specification,
which defines command buffer address with two 32-bit fields.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Reviewed-by: Peter Huewe <peterhuewe@....de>
Signed-off-by: Peter Huewe <peterhuewe@....de>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/char/tpm/tpm_crb.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 1267322..83068fa 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -74,7 +74,8 @@ struct crb_control_area {
 	u32 int_enable;
 	u32 int_sts;
 	u32 cmd_size;
-	u64 cmd_pa;
+	u32 cmd_pa_low;
+	u32 cmd_pa_high;
 	u32 rsp_size;
 	u64 rsp_pa;
 } __packed;
@@ -273,8 +274,8 @@ static int crb_acpi_add(struct acpi_device *device)
 		return -ENOMEM;
 	}
 
-	memcpy_fromio(&pa, &priv->cca->cmd_pa, 8);
-	pa = le64_to_cpu(pa);
+	pa = ((u64) le32_to_cpu(ioread32(&priv->cca->cmd_pa_high)) << 32) |
+		(u64) le32_to_cpu(ioread32(&priv->cca->cmd_pa_low));
 	priv->cmd = devm_ioremap_nocache(dev, pa,
 					 ioread32(&priv->cca->cmd_size));
 	if (!priv->cmd) {
-- 
1.9.1

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