[Openvpn-devel] Return NULL if GetAdaptersInfo fails

Message ID 1514952123-26616-1-git-send-email-selva.nair@gmail.com
State Accepted
Headers show
Series
  • [Openvpn-devel] Return NULL if GetAdaptersInfo fails
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Commit Message

Selva Nair Jan. 3, 2018, 4:02 a.m.
From: Selva Nair <selva.nair@gmail.com>

- Currently a pointer to potentially uninitialized IP_ADAPTER_INFO
  struct is returned on error causing ill-defined behaviour.

Signed-off-by: Selva Nair <selva.nair@gmail.com>
---

There have been some reports of unexpected failure in GetAdaptersInfo.
When and why that happens is still unclear but this bug could explain
why the process goes into a tailspin in such occasions.

 src/openvpn/tun.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

Comments

Steffan Karger Jan. 3, 2018, 8:10 a.m. | #1
Hi,

On 03-01-18 05:02, selva.nair@gmail.com wrote:
> From: Selva Nair <selva.nair@gmail.com>
> 
> - Currently a pointer to potentially uninitialized IP_ADAPTER_INFO
>   struct is returned on error causing ill-defined behaviour.
> 
> Signed-off-by: Selva Nair <selva.nair@gmail.com>
> ---
> 
> There have been some reports of unexpected failure in GetAdaptersInfo.
> When and why that happens is still unclear but this bug could explain
> why the process goes into a tailspin in such occasions.
> 
>  src/openvpn/tun.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c
> index 25831ce..6e16348 100644
> --- a/src/openvpn/tun.c
> +++ b/src/openvpn/tun.c
> @@ -4178,15 +4178,12 @@ get_adapter_info_list(struct gc_arena *gc)
>      else
>      {
>          pi = (PIP_ADAPTER_INFO) gc_malloc(size, false, gc);
> -        if ((status = GetAdaptersInfo(pi, &size)) == NO_ERROR)
> -        {
> -            return pi;
> -        }
> -        else
> +        if ((status = GetAdaptersInfo(pi, &size)) != NO_ERROR)
>          {
>              msg(M_INFO, "GetAdaptersInfo #2 failed (status=%u) : %s",
>                  (unsigned int)status,
>                  strerror_win32(status, gc));
> +            pi = NULL;
>          }
>      }
>      return pi;
> 

Less lines, *and* less bugs.  Very good.

Acked-by: Steffan Karger <steffan.karger@fox-it.com>

-Steffan

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Simon Rozman Jan. 3, 2018, 8:15 a.m. | #2
Hi,

> -----Original Message-----
> From: selva.nair@gmail.com [mailto:selva.nair@gmail.com]
> Sent: Wednesday, January 03, 2018 5:02 AM
> To: openvpn-devel@lists.sourceforge.net
> Subject: [Openvpn-devel] [PATCH] Return NULL if GetAdaptersInfo fails
> 
> From: Selva Nair <selva.nair@gmail.com>
> 
> - Currently a pointer to potentially uninitialized IP_ADAPTER_INFO
>   struct is returned on error causing ill-defined behaviour.
> 
> Signed-off-by: Selva Nair <selva.nair@gmail.com>
> ---
> 
> There have been some reports of unexpected failure in GetAdaptersInfo.
> When and why that happens is still unclear but this bug could explain why
the
> process goes into a tailspin in such occasions.
> 
>  src/openvpn/tun.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c index 25831ce..6e16348
> 100644
> --- a/src/openvpn/tun.c
> +++ b/src/openvpn/tun.c
> @@ -4178,15 +4178,12 @@ get_adapter_info_list(struct gc_arena *gc)
>      else
>      {
>          pi = (PIP_ADAPTER_INFO) gc_malloc(size, false, gc);
> -        if ((status = GetAdaptersInfo(pi, &size)) == NO_ERROR)
> -        {
> -            return pi;
> -        }
> -        else
> +        if ((status = GetAdaptersInfo(pi, &size)) != NO_ERROR)
>          {
>              msg(M_INFO, "GetAdaptersInfo #2 failed (status=%u) : %s",
>                  (unsigned int)status,
>                  strerror_win32(status, gc));
> +            pi = NULL;
>          }
>      }
>      return pi;
> --
> 2.1.4
> 
> 
>
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I have reviewed the program flow after each get_adapter_info_list() function
call. All code to use the return value of get_adapter_info_list() indeed
checks the return value for non-NULL before using it.

Acked-by: Simon Rozman <simon@rozman.si>

Regards,
Simon
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Gert Doering Jan. 9, 2018, 3:19 p.m. | #3
Thanks.

Your patch has been applied to the master and release/2.4 branch.

commit 5050c5b1ec3f2aa04140ab83f2498b3329381ee4 (master)
commit d2b9bd80bab7ce56ada09b0df1c2baec8b029d93 (release/2.4)
Author: Selva Nair
Date:   Tue Jan 2 23:02:03 2018 -0500

     Return NULL if GetAdaptersInfo fails

     Signed-off-by: Selva Nair <selva.nair@gmail.com>
     Acked-by: Steffan Karger <steffan.karger@fox-it.com>
     Acked-by: Simon Rozman <simon@rozman.si>
     Message-Id: <1514952123-26616-1-git-send-email-selva.nair@gmail.com>
     URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg16139.html
     Signed-off-by: Gert Doering <gert@greenie.muc.de>


--
kind regards,

Gert Doering


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Patch

diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c
index 25831ce..6e16348 100644
--- a/src/openvpn/tun.c
+++ b/src/openvpn/tun.c
@@ -4178,15 +4178,12 @@  get_adapter_info_list(struct gc_arena *gc)
     else
     {
         pi = (PIP_ADAPTER_INFO) gc_malloc(size, false, gc);
-        if ((status = GetAdaptersInfo(pi, &size)) == NO_ERROR)
-        {
-            return pi;
-        }
-        else
+        if ((status = GetAdaptersInfo(pi, &size)) != NO_ERROR)
         {
             msg(M_INFO, "GetAdaptersInfo #2 failed (status=%u) : %s",
                 (unsigned int)status,
                 strerror_win32(status, gc));
+            pi = NULL;
         }
     }
     return pi;