Re: [Minios-devel] [UNIKRAFT PATCH v2 2/2] lib/vfscore: fix null pointer dereferences

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

Reviewed-by: Sharan Santhanam <sharan.santhanam@xxxxxxxxx>

On 3/8/20 2:24 PM, Hugo Lefeuvre wrote:
> futimesat allocates buffers via malloc and dereference returned
> pointers without NULL checking, causing crashes in OOM situations.
>
> Return EFAULT as this appears to be the most appropriate error code in
> this case (the posix definition does include ENOMEM as a possible
> error code).
>
> Signed-off-by: Hugo Lefeuvre <hugo.lefeuvre@xxxxxxxxx>
> ---
> Changed since v1:
>   - return EFAULT instead of ENOMEM
>
> diff --git a/lib/vfscore/main.c b/lib/vfscore/main.c
> index 7a7a54c..8c80ea6 100644
> --- a/lib/vfscore/main.c
> +++ b/lib/vfscore/main.c
> @@ -1803,6 +1803,12 @@ int futimesat(int dirfd, const char *pathname, const 
> struct timeval times[2])
>   
>   	/* build absolute path */
>         absolute_path = (char*)malloc(PATH_MAX);
> +       if (!absolute_path) {
> +               fdrop(fp);
> +               error = EFAULT;
> +               goto out_errno;
> +       }
> +
>         strlcpy(absolute_path, fp->f_dentry->d_mount->m_path, PATH_MAX);
>         strlcat(absolute_path, fp->f_dentry->d_path, PATH_MAX);
>   
>
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