[V9fs-developer] [PATCH] version pointer uninitialized

[V9fs-developer] [PATCH] version pointer uninitialized

[Tomas Bortoli]

The p9_client_version() does not initialize the version
pointer. If the call to p9pdu_readf() returns an error and version has not
been allocated in p9pdu_readf(), then the program will jump to the "error"
label and will try to free the version pointer. If version is not
initialized, free() will be called with uninitialized, garbage data and
will provoke a crash.

Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com
---
 net/9p/client.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/9p/client.c b/net/9p/client.c
index 18c5271910dc..40f7c47f2f74 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -957,7 +957,7 @@ static int p9_client_version(struct p9_client *c)
 {
 	int err = 0;
 	struct p9_req_t *req;
-	char *version;
+	char *version = NULL;
 	int msize;
 
 	p9_debug(P9_DEBUG_9P, ">>> TVERSION msize %d protocol %d\n",
-- 
2.11.0

Re: [V9fs-developer] [PATCH] version pointer uninitialized

[piaojun]

LGTM

On 2018/7/10 6:29, Tomas Bortoli wrote:
> The p9_client_version() does not initialize the version
> pointer. If the call to p9pdu_readf() returns an error and version has not
> been allocated in p9pdu_readf(), then the program will jump to the "error"
> label and will try to free the version pointer. If version is not
> initialized, free() will be called with uninitialized, garbage data and
> will provoke a crash.
> 
> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
> Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com
Reviewed-by: Jun Piao <piaojun@huawei.com>
> ---
>  net/9p/client.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/9p/client.c b/net/9p/client.c
> index 18c5271910dc..40f7c47f2f74 100644
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -957,7 +957,7 @@ static int p9_client_version(struct p9_client *c)
>  {
>  	int err = 0;
>  	struct p9_req_t *req;
> -	char *version;
> +	char *version = NULL;
>  	int msize;
>  
>  	p9_debug(P9_DEBUG_9P, ">>> TVERSION msize %d protocol %d\n",
> 

Re: [V9fs-developer] [PATCH] version pointer uninitialized

[jiangyiwen]

On 2018/7/10 6:29, Tomas Bortoli wrote:
> The p9_client_version() does not initialize the version
> pointer. If the call to p9pdu_readf() returns an error and version has not
> been allocated in p9pdu_readf(), then the program will jump to the "error"
> label and will try to free the version pointer. If version is not
> initialized, free() will be called with uninitialized, garbage data and
> will provoke a crash.
> 
> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>

Reviewed-by: Yiwen Jiang <jiangyiwen@huawei.com>

> Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com
> ---
>  net/9p/client.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/9p/client.c b/net/9p/client.c
> index 18c5271910dc..40f7c47f2f74 100644
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -957,7 +957,7 @@ static int p9_client_version(struct p9_client *c)
>  {
>  	int err = 0;
>  	struct p9_req_t *req;
> -	char *version;
> +	char *version = NULL;
>  	int msize;
>  
>  	p9_debug(P9_DEBUG_9P, ">>> TVERSION msize %d protocol %d\n",
> 

Re: [V9fs-developer] [PATCH] version pointer uninitialized

[Tomas Bortoli]

On 07/11/2018 03:26 AM, jiangyiwen wrote:
> On 2018/7/10 6:29, Tomas Bortoli wrote:
>> The p9_client_version() does not initialize the version
>> pointer. If the call to p9pdu_readf() returns an error and version has not
>> been allocated in p9pdu_readf(), then the program will jump to the "error"
>> label and will try to free the version pointer. If version is not
>> initialized, free() will be called with uninitialized, garbage data and
>> will provoke a crash.
>>
>> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
> Reviewed-by: Yiwen Jiang <jiangyiwen@huawei.com>
>
>> Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com
>> ---
>>  net/9p/client.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/9p/client.c b/net/9p/client.c
>> index 18c5271910dc..40f7c47f2f74 100644
>> --- a/net/9p/client.c
>> +++ b/net/9p/client.c
>> @@ -957,7 +957,7 @@ static int p9_client_version(struct p9_client *c)
>>  {
>>  	int err = 0;
>>  	struct p9_req_t *req;
>> -	char *version;
>> +	char *version = NULL;
>>  	int msize;
>>  
>>  	p9_debug(P9_DEBUG_9P, ">>> TVERSION msize %d protocol %d\n",
>>
>

+ Cc: Andrew Morton <akpm@linux-foundation.org>

This goes with the other patch: [V9fs-developer] [PATCH]
p9_parse_header() validate PDU length

Tomas