[PATCH] libfdt: fix fdt_check_node_offset_ w/ VALID_INPUT

[PATCH] libfdt: fix fdt_check_node_offset_ w/ VALID_INPUT

[Frank Mehnert]

fdt_check_node_offset_() checks for a valid offset but also changes the
offset by calling fdt_next_tag(). Hence, do not skip this function if
ASSUME_VALID_INPUT is set.

Actually this works similar to fdt_check_prop_offset_().
---
 libfdt/fdt.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/libfdt/fdt.c b/libfdt/fdt.c
index c28fcc1..39ed8ed 100644
--- a/libfdt/fdt.c
+++ b/libfdt/fdt.c
@@ -206,8 +206,6 @@ uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)

 int fdt_check_node_offset_(const void *fdt, int offset)
 {
-       if (can_assume(VALID_INPUT))
-               return offset;
        if ((offset < 0) || (offset % FDT_TAGSIZE)
            || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
                return -FDT_ERR_BADOFFSET;

Re: [PATCH] libfdt: fix fdt_check_node_offset_ w/ VALID_INPUT

[David Gibson]

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On Thu, Aug 13, 2020 at 09:55:09AM +0200, Frank Mehnert wrote:
> fdt_check_node_offset_() checks for a valid offset but also changes the
> offset by calling fdt_next_tag(). Hence, do not skip this function if
> ASSUME_VALID_INPUT is set.
> 
> Actually this works similar to fdt_check_prop_offset_().

Correct, but we can do better.  We can still elide the checks for
offset < 0 and offset % FDT_TAGSIZE when VALID_INPUT is set.

> ---
>  libfdt/fdt.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/libfdt/fdt.c b/libfdt/fdt.c
> index c28fcc1..39ed8ed 100644
> --- a/libfdt/fdt.c
> +++ b/libfdt/fdt.c
> @@ -206,8 +206,6 @@ uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
> 
>  int fdt_check_node_offset_(const void *fdt, int offset)
>  {
> -       if (can_assume(VALID_INPUT))
> -               return offset;
>         if ((offset < 0) || (offset % FDT_TAGSIZE)
>             || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
>                 return -FDT_ERR_BADOFFSET;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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Re: [PATCH] libfdt: fix fdt_check_node_offset_ w/ VALID_INPUT

[Frank Mehnert]

fdt_check_node_offset_() checks for a valid offset but also changes the
offset by calling fdt_next_tag(). Hence, do not skip this function if
ASSUME_VALID_INPUT is set but only omit the initial offset check in that
case.

As this function works very similar to fdt_check_prop_offset_(), do the
offset check there as well depending on ASSUME_VALID_INPUT.
---
 libfdt/fdt.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/libfdt/fdt.c b/libfdt/fdt.c
index c28fcc1..37b7b93 100644
--- a/libfdt/fdt.c
+++ b/libfdt/fdt.c
@@ -206,10 +206,11 @@ uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)

 int fdt_check_node_offset_(const void *fdt, int offset)
 {
-       if (can_assume(VALID_INPUT))
-               return offset;
-       if ((offset < 0) || (offset % FDT_TAGSIZE)
-           || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
+       if (!can_assume(VALID_INPUT)
+           && ((offset < 0) || (offset % FDT_TAGSIZE)))
+               return -FDT_ERR_BADOFFSET;
+
+       if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
                return -FDT_ERR_BADOFFSET;

        return offset;
@@ -217,8 +218,11 @@ int fdt_check_node_offset_(const void *fdt, int offset)

 int fdt_check_prop_offset_(const void *fdt, int offset)
 {
-       if ((offset < 0) || (offset % FDT_TAGSIZE)
-           || (fdt_next_tag(fdt, offset, &offset) != FDT_PROP))
+       if (!can_assume(VALID_INPUT)
+           && ((offset < 0) || (offset % FDT_TAGSIZE)))
+               return -FDT_ERR_BADOFFSET;
+
+       if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
                return -FDT_ERR_BADOFFSET;

        return offset;

Re: [PATCH] libfdt: fix fdt_check_node_offset_ w/ VALID_INPUT

[David Gibson]

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On Thu, Aug 13, 2020 at 05:26:26PM +0200, Frank Mehnert wrote:
> fdt_check_node_offset_() checks for a valid offset but also changes the
> offset by calling fdt_next_tag(). Hence, do not skip this function if
> ASSUME_VALID_INPUT is set but only omit the initial offset check in that
> case.
> 
> As this function works very similar to fdt_check_prop_offset_(), do the
> offset check there as well depending on ASSUME_VALID_INPUT.

So, it looks like your mailer has mangled the patch (replacing tabs
with spaces).  Since it's simple, I fixed it up this time, though.

Applied.

> ---
>  libfdt/fdt.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/libfdt/fdt.c b/libfdt/fdt.c
> index c28fcc1..37b7b93 100644
> --- a/libfdt/fdt.c
> +++ b/libfdt/fdt.c
> @@ -206,10 +206,11 @@ uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
> 
>  int fdt_check_node_offset_(const void *fdt, int offset)
>  {
> -       if (can_assume(VALID_INPUT))
> -               return offset;
> -       if ((offset < 0) || (offset % FDT_TAGSIZE)
> -           || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
> +       if (!can_assume(VALID_INPUT)
> +           && ((offset < 0) || (offset % FDT_TAGSIZE)))
> +               return -FDT_ERR_BADOFFSET;
> +
> +       if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
>                 return -FDT_ERR_BADOFFSET;
> 
>         return offset;
> @@ -217,8 +218,11 @@ int fdt_check_node_offset_(const void *fdt, int offset)
> 
>  int fdt_check_prop_offset_(const void *fdt, int offset)
>  {
> -       if ((offset < 0) || (offset % FDT_TAGSIZE)
> -           || (fdt_next_tag(fdt, offset, &offset) != FDT_PROP))
> +       if (!can_assume(VALID_INPUT)
> +           && ((offset < 0) || (offset % FDT_TAGSIZE)))
> +               return -FDT_ERR_BADOFFSET;
> +
> +       if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
>                 return -FDT_ERR_BADOFFSET;
> 
>         return offset;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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Re: [PATCH] libfdt: fix fdt_check_node_offset_ w/ VALID_INPUT

[Frank Mehnert]

On Freitag, 14. August 2020 05:17:48 CEST David Gibson wrote:
> On Thu, Aug 13, 2020 at 05:26:26PM +0200, Frank Mehnert wrote:
> > fdt_check_node_offset_() checks for a valid offset but also changes the
> > offset by calling fdt_next_tag(). Hence, do not skip this function if
> > ASSUME_VALID_INPUT is set but only omit the initial offset check in that
> > case.
> > 
> > As this function works very similar to fdt_check_prop_offset_(), do the
> > offset check there as well depending on ASSUME_VALID_INPUT.
> 
> So, it looks like your mailer has mangled the patch (replacing tabs
> with spaces).  Since it's simple, I fixed it up this time, though.
> 
> Applied.

Thanks!

Frank
-- 
Dr.-Ing. Frank Mehnert, frank.mehnert-2ptZNfhJYoRaodhZ+FW2PA@public.gmane.org, +49-351-41 883 224

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