[PATCH 3.19.y-ckt 163/164] TPM: Avoid reference to potentially freed memory

[Kamal Mostafa]

3.19.8-ckt11 -stable review patch.  If anyone has any objections, please let me know.

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

From: Christophe JAILLET <christophe.jaillet at wanadoo.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 at wanadoo.fr>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen at linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen at linux.intel.com>
Acked-by: Peter Huewe <PeterHuewe at gmx.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.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 98ba2bd..565a0b3 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