Re: [Xen-devel] [PATCH] tools/libxl: Fix leaking ssid_label in libxl_name_to_domid

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Sat, Jan 26, 2019 at 10:45:07PM -0700, Tamas K Lengyel wrote:
> On systems with XSM enabled libxl_name_to_domid leaks memory
> allocated for ssid_label:
> 
> ==2693== 53 bytes in 2 blocks are definitely lost in loss record 4 of 8
> ==2693==    at 0x4C2BE6D: malloc (vg_replace_malloc.c:309)
> ==2693==    by 0x6C0A3B9: strdup (strdup.c:42)
> ==2693==    by 0x5108294: libxl_flask_sid_to_context (libxl_flask.c:39)
> ==2693==    by 0x50C2B64: libxl__xcinfo2xlinfo (libxl_domain.c:267)
> ==2693==    by 0x50C2E02: libxl_list_domain (libxl_domain.c:308)
> ==2693==    by 0x508A3C5: libxl_name_to_domid (libxl_utils.c:77)
> 
> Signed-off-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
>  tools/libxl/libxl_utils.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
> index e50e094c48..99abfa5497 100644
> --- a/tools/libxl/libxl_utils.c
> +++ b/tools/libxl/libxl_utils.c
> @@ -79,6 +79,8 @@ int libxl_name_to_domid(libxl_ctx *ctx, const char *name,
>          return ERROR_NOMEM;
>  
>      for (i = 0; i < nb_domains; i++) {
> +        if (dominfo[i].ssid_label)
> +            free(dominfo[i].ssid_label);
>          domname = libxl_domid_to_name(ctx, dominfo[i].domid);
>          if (!domname)
>              continue;

Thanks for reporting this issue. I think your patch isn't future-proof.

Can you try the following patch?

---8<---
From fc9f9ad912cb61085a5bfb60aef3643dcd82a496 Mon Sep 17 00:00:00 2001
From: Wei Liu <wei.liu2@xxxxxxxxxx>
Date: Mon, 28 Jan 2019 12:10:12 +0000
Subject: [PATCH] libxl: correctly dispose of dominfo list in
 libxl_name_to_domid

Tamas reported ssid_label was leaked. Use the designated function to
free dominfo list to fix the leakage.

Reported-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl_utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
index e50e094c48..f360f5e228 100644
--- a/tools/libxl/libxl_utils.c
+++ b/tools/libxl/libxl_utils.c
@@ -90,7 +90,7 @@ int libxl_name_to_domid(libxl_ctx *ctx, const char *name,
         }
         free(domname);
     }
-    free(dominfo);
+    libxl_dominfo_list_free(dominfo, nb_domains);
     return ret;
 }
 
-- 
2.11.0


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