linux-kernel - [PATCH 1/3] TPM: Avoid reference to potentially freed memory

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Message-Id: <1446718824-5249-2-git-send-email-jarkko.sakkinen@linux.intel.com>
Date:	Thu,  5 Nov 2015 12:20:21 +0200
From:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:	Peter Huewe <peterhuewe@....de>,
	Marcel Selhorst <tpmdd@...horst.net>
Cc:	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
	tpmdd-devel@...ts.sourceforge.net (moderated list:TPM DEVICE DRIVER),
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/3] TPM: Avoid reference to potentially freed memory

From: Christophe JAILLET <christophe.jaillet@...adoo.fr>

Reference to the 'np' node is dropped before dereferencing the 'sizep' and
'basep' pointers, which could by then point to junk if the node has been
freed.

Refactor code to call 'of_node_put' later.

Fixes: c5df39262dd5 ("drivers/char/tpm: Add securityfs support for event log")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
---
 drivers/char/tpm/tpm_of.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
index 1141456..570f30c 100644
--- a/drivers/char/tpm/tpm_of.c
+++ b/drivers/char/tpm/tpm_of.c
@@ -53,17 +53,18 @@ int read_log(struct tpm_bios_log *log)
 		goto cleanup_eio;
 	}
 
-	of_node_put(np);
 	log->bios_event_log = kmalloc(*sizep, GFP_KERNEL);
 	if (!log->bios_event_log) {
 		pr_err("%s: ERROR - Not enough memory for BIOS measurements\n",
 		       __func__);
+		of_node_put(np);
 		return -ENOMEM;
 	}
 
 	log->bios_event_log_end = log->bios_event_log + *sizep;
 
 	memcpy(log->bios_event_log, __va(*basep), *sizep);
+	of_node_put(np);
 
 	return 0;
 
-- 
2.5.0

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