Patchwork net: irda: using kzalloc() instead of kmalloc() to avoid strncpy() issue.

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Submitter Chen Gang
Date May 17, 2013, 9:13 a.m.
Message ID <5195F4A0.3000708@asianux.com>
Download mbox | patch
Permalink /patch/244545/
State Accepted
Delegated to: David Miller
Headers show

Comments

Chen Gang - May 17, 2013, 9:13 a.m.
'discovery->data.info' length is 22, NICKNAME_MAX_LEN is 21, so the
strncpy() will always left the last byte of 'discovery->data.info'
uninitialized.

When 'text' length is longer than 21 (NICKNAME_MAX_LEN), if still left
the last byte of 'discovery->data.info' uninitialized, the next
strlen() will cause issue.

Also 'discovery->data' is 'struct irda_device_info' which defined in
"include/uapi/...", it may copy to user mode, so need whole initialized.

All together, need use kzalloc() instead of kmalloc() to initialize all
members firstly.


Signed-off-by: Chen Gang <gang.chen@asianux.com>
---
 net/irda/irlap_frame.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
David Miller - May 19, 2013, 10:11 p.m.
From: Chen Gang <gang.chen@asianux.com>
Date: Fri, 17 May 2013 17:13:04 +0800

> 
> 'discovery->data.info' length is 22, NICKNAME_MAX_LEN is 21, so the
> strncpy() will always left the last byte of 'discovery->data.info'
> uninitialized.
> 
> When 'text' length is longer than 21 (NICKNAME_MAX_LEN), if still left
> the last byte of 'discovery->data.info' uninitialized, the next
> strlen() will cause issue.
> 
> Also 'discovery->data' is 'struct irda_device_info' which defined in
> "include/uapi/...", it may copy to user mode, so need whole initialized.
> 
> All together, need use kzalloc() instead of kmalloc() to initialize all
> members firstly.
> 
> Signed-off-by: Chen Gang <gang.chen@asianux.com>

Applied, thanks.
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Chen Gang - May 20, 2013, 1:04 a.m.
On 05/20/2013 06:11 AM, David Miller wrote:
> From: Chen Gang <gang.chen@asianux.com>
> Date: Fri, 17 May 2013 17:13:04 +0800
> 
>> > 
>> > 'discovery->data.info' length is 22, NICKNAME_MAX_LEN is 21, so the
>> > strncpy() will always left the last byte of 'discovery->data.info'
>> > uninitialized.
>> > 
>> > When 'text' length is longer than 21 (NICKNAME_MAX_LEN), if still left
>> > the last byte of 'discovery->data.info' uninitialized, the next
>> > strlen() will cause issue.
>> > 
>> > Also 'discovery->data' is 'struct irda_device_info' which defined in
>> > "include/uapi/...", it may copy to user mode, so need whole initialized.
>> > 
>> > All together, need use kzalloc() instead of kmalloc() to initialize all
>> > members firstly.
>> > 
>> > Signed-off-by: Chen Gang <gang.chen@asianux.com>
> Applied, thanks.
> 
> 

Thank you, too.


Thanks.

Patch

diff --git a/net/irda/irlap_frame.c b/net/irda/irlap_frame.c
index 8c00416..9ea0c93 100644
--- a/net/irda/irlap_frame.c
+++ b/net/irda/irlap_frame.c
@@ -544,7 +544,7 @@  static void irlap_recv_discovery_xid_cmd(struct irlap_cb *self,
 		/*
 		 *  We now have some discovery info to deliver!
 		 */
-		discovery = kmalloc(sizeof(discovery_t), GFP_ATOMIC);
+		discovery = kzalloc(sizeof(discovery_t), GFP_ATOMIC);
 		if (!discovery) {
 			IRDA_WARNING("%s: unable to malloc!\n", __func__);
 			return;