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[3/5] powerpc/powernv: Check sysfs size before copying

Message ID 1398324337-896-4-git-send-email-joel@jms.id.au (mailing list archive)
State Accepted
Commit 85390378f0a6abf3bdb10c3d504d77862a2d0ec9
Delegated to: Benjamin Herrenschmidt
Headers show

Commit Message

Joel Stanley April 24, 2014, 7:25 a.m. UTC 
The sysparam code currently uses the userspace supplied number of
bytes when memcpy()ing in to a local 64-byte buffer.

Limit the maximum number of bytes by the size of the buffer.
---
 arch/powerpc/platforms/powernv/opal-sysparam.c | 4 ++++
 1 file changed, 4 insertions(+)
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Patch

diff --git a/arch/powerpc/platforms/powernv/opal-sysparam.c b/arch/powerpc/platforms/powernv/opal-sysparam.c
index a363c53..21fdc0a 100644
--- a/arch/powerpc/platforms/powernv/opal-sysparam.c
+++ b/arch/powerpc/platforms/powernv/opal-sysparam.c
@@ -135,6 +135,10 @@  static ssize_t sys_param_store(struct kobject *kobj,
 			kobj_attr);
 	ssize_t ret;
 
+        /* MAX_PARAM_DATA_LEN is sizeof(param_data_buf) */
+        if (count > MAX_PARAM_DATA_LEN)
+                count = MAX_PARAM_DATA_LEN;
+
 	mutex_lock(&opal_sysparam_mutex);
 	memcpy(param_data_buf, buf, count);
 	ret = opal_set_sys_param(attr->param_id, attr->param_size,