Re: [Minios-devel] [UNIKRAFT PATCH] lib/vfscore: fix null pointer dereference

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

Patch seems fine. Good spot!!

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

On 2/20/20 9:31 PM, Hugo Lefeuvre wrote:
> fhold(fp) is called before checking for !fp, leading to null pointer
> dereference if the allocation can't be satisfied. Make sure to check
> for !fp before doing anything with this pointer.
>
> Signed-off-by: Hugo Lefeuvre <hugo.lefeuvre@xxxxxxxxx>
> ---
>   lib/vfscore/syscalls.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/vfscore/syscalls.c b/lib/vfscore/syscalls.c
> index 11813db..9b5a6bd 100644
> --- a/lib/vfscore/syscalls.c
> +++ b/lib/vfscore/syscalls.c
> @@ -198,11 +198,11 @@ sys_open(char *path, int flags, mode_t mode, struct 
> vfscore_file **fpp)
>         }
>   
>   	fp = calloc(sizeof(struct vfscore_file), 1);
> -       fhold(fp);
>         if (!fp) {
>             error = ENOMEM;
>             goto out_vn_unlock;
>         }
> +       fhold(fp);
>         fp->f_flags = flags;
>   
>   	// OSv was using a intrusive_ptr which was increasing the refcount
>
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