Re: [Qemu-devel] [PATCH 2/2] 9pfs: fix memory leak about xattr value

[Greg Kurz <groug@kaod.org>]

On Sat,  8 Oct 2016 22:27:08 -0700
Li Qiang <liq3ea@gmail.com> wrote:

> From: Li Qiang <liqiang6-s@360.cn>
> 
> The 'fs.xattr.value' field in V9fsFidState object doesn't consider
> the situation that this field has been allocated previously. Every
> time, it will be allocated directly. This leads a  host memory leak
> issue. This patch fix this.
> 

This cannot happen because v9fs_xattrwalk() always allocates this fid:

    xattr_fidp = alloc_fid(s, newfid);
    if (xattr_fidp == NULL) {
        err = -EINVAL;
        goto out;
    }

> Signed-off-by: Li Qiang <liqiang6-s@360.cn>
> ---
>  hw/9pfs/9p.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index 8751c19..3af23f9 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -350,6 +350,7 @@ free_out:
>      v9fs_string_free(&fidp->fs.xattr.name);
>  free_value:
>      g_free(fidp->fs.xattr.value);
> +    fidp->fs.xattr.value = NULL;
>      return retval;
>  }
>  
> @@ -3191,7 +3192,8 @@ static void v9fs_xattrwalk(void *opaque)
>          xattr_fidp->fid_type = P9_FID_XATTR;
>          xattr_fidp->fs.xattr.copied_len = -1;
>          if (size) {
> -            xattr_fidp->fs.xattr.value = g_malloc(size);
> +            xattr_fidp->fs.xattr.value = g_realloc(
> +                xattr_fidp->fs.xattr.value, size);
>              err = v9fs_co_llistxattr(pdu, &xattr_fidp->path,
>                                       xattr_fidp->fs.xattr.value,
>                                       xattr_fidp->fs.xattr.len);
> @@ -3224,7 +3226,8 @@ static void v9fs_xattrwalk(void *opaque)
>          xattr_fidp->fid_type = P9_FID_XATTR;
>          xattr_fidp->fs.xattr.copied_len = -1;
>          if (size) {
> -            xattr_fidp->fs.xattr.value = g_malloc(size);
> +            xattr_fidp->fs.xattr.value = g_realloc(
> +                xattr_fidp->fs.xattr.value, size);
>              err = v9fs_co_lgetxattr(pdu, &xattr_fidp->path,
>                                      &name, xattr_fidp->fs.xattr.value,
>                                      xattr_fidp->fs.xattr.len);