linux-kernel - [PATCH 4.2.y-ckt 177/211] TPM: Avoid reference to potentially freed memory

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Message-Id: <1452023119-25647-178-git-send-email-kamal@canonical.com>
Date:	Tue,  5 Jan 2016 11:44:45 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 177/211] TPM: Avoid reference to potentially freed memory

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

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

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

commit eb8ed1eb9a158c460d10205eaff71fd4ac67c160 upstream.

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>
Acked-by: Peter Huewe <PeterHuewe@....de>
Signed-off-by: Kamal Mostafa <kamal@...onical.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 eebe625..40f4150 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(be64_to_cpup(basep)), *sizep);
+	of_node_put(np);
 
 	return 0;
 
-- 
1.9.1

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