Re: [PATCH 10/21] hw/core: Fix latent fit_load_fdt() error handling bug

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

30.11.2019 22:42, Markus Armbruster wrote:
> fit_load_fdt() recovers from fit_image_addr() failing with ENOENT.
> Except it doesn't when its @errp argument is &error_fatal or
> &error_abort, because it blindly passes @errp to fit_image_addr().
> Messed up in commit 3eb99edb48 "loader-fit: Wean off error_printf()".
> 
> The bug can't bite as no caller actually passes &error_fatal or
> &error_abort.  Fix it anyway.
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Hmm, actually it makes my
"[PATCH v7 01/21] hw/core/loader-fit: fix freeing errp in fit_load_fdt"
unnecessary. If you want you may drop my 01 (as it covers less problems),
and in this case you may note in your cover letter, that
errp = NULL is broken here too (may be nobady pass it?),
and normal errp is handled wrong, as *errp doesn't set to NULL after
error_free(*errp) (still, the only caller rely on return value more than on
err, so the problem can't be triggered with current code)

> ---
>   hw/core/loader-fit.c | 15 ++++++++-------
>   1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/core/loader-fit.c b/hw/core/loader-fit.c
> index 953b16bc82..c465921b8f 100644
> --- a/hw/core/loader-fit.c
> +++ b/hw/core/loader-fit.c
> @@ -178,11 +178,12 @@ static int fit_load_fdt(const struct fit_loader *ldr, const void *itb,
>                           int cfg, void *opaque, const void *match_data,
>                           hwaddr kernel_end, Error **errp)
>   {
> +    Error *err = NULL;
>       const char *name;
>       const void *data;
>       const void *load_data;
>       hwaddr load_addr;
> -    int img_off, err;
> +    int img_off;
>       size_t sz;
>       int ret;
>   
> @@ -197,13 +198,13 @@ static int fit_load_fdt(const struct fit_loader *ldr, const void *itb,
>           return -EINVAL;
>       }
>   
> -    err = fit_image_addr(itb, img_off, "load", &load_addr, errp);
> -    if (err == -ENOENT) {
> +    ret = fit_image_addr(itb, img_off, "load", &load_addr, &err);
> +    if (ret == -ENOENT) {
>           load_addr = ROUND_UP(kernel_end, 64 * KiB) + (10 * MiB);
> -        error_free(*errp);
> -    } else if (err) {
> -        error_prepend(errp, "unable to read FDT load address from FIT: ");
> -        ret = err;
> +        error_free(err);
> +    } else if (ret) {
> +        error_propagate_prepend(errp, err,
> +                                "unable to read FDT load address from FIT: ");
>           goto out;
>       }
>   
> 

So much attention to that function :)

I'd also propose the following:

diff --git a/hw/core/loader-fit.c b/hw/core/loader-fit.c
index c465921b8f..2c9efeef7a 100644
--- a/hw/core/loader-fit.c
+++ b/hw/core/loader-fit.c
@@ -180,8 +180,8 @@ static int fit_load_fdt(const struct fit_loader *ldr, const void *itb,
  {
      Error *err = NULL;
      const char *name;
-    const void *data;
-    const void *load_data;
+    void *data;
+    void *load_data;
      hwaddr load_addr;
      int img_off;
      size_t sz;
@@ -218,9 +218,9 @@ static int fit_load_fdt(const struct fit_loader *ldr, const void *itb,

      ret = 0;
  out:
-    g_free((void *) data);
+    g_free(data);
      if (data != load_data) {
-        g_free((void *) load_data);
+        g_free(load_data);
      }
      return ret;
  }


Or, even better:

--- a/hw/core/loader-fit.c
+++ b/hw/core/loader-fit.c
@@ -180,7 +180,8 @@ static int fit_load_fdt(const struct fit_loader *ldr, const void *itb,
  {
      Error *err = NULL;
      const char *name;
-    const void *data;
+    g_autofree void *data = NULL;
+    g_autofree void *fdt_filter_data = NULL;
      const void *load_data;
      hwaddr load_addr;
      int img_off;
@@ -202,27 +203,23 @@ static int fit_load_fdt(const struct fit_loader *ldr, const void *itb,
      if (ret == -ENOENT) {
          load_addr = ROUND_UP(kernel_end, 64 * KiB) + (10 * MiB);
          error_free(err);
+        return 0;
      } else if (ret) {
          error_propagate_prepend(errp, err,
                                  "unable to read FDT load address from FIT: ");
-        goto out;
+        return ret;
      }

      if (ldr->fdt_filter) {
-        load_data = ldr->fdt_filter(opaque, data, match_data, &load_addr);
+        load_data = fdt_filter_data =
+                ldr->fdt_filter(opaque, data, match_data, &load_addr);
      }

      load_addr = ldr->addr_to_phys(opaque, load_addr);
      sz = fdt_totalsize(load_data);
      rom_add_blob_fixed(name, load_data, sz, load_addr);

-    ret = 0;
-out:
-    g_free((void *) data);
-    if (data != load_data) {
-        g_free((void *) load_data);
-    }
-    return ret;
+    return 0;
  }




-- 
Best regards,
Vladimir