On Mon, Nov 12, 2018 at 02:00:16AM +0530, Bhupesh Sharma wrote:
> Vicenç reported (via [1]) that currently executing kexec with
> '--dtb' option and passing a .dtb which doesn't have a '/chosen' node
> leads to the following error:
>
> # kexec -d --dtb dtb_without_chosen_node.dtb --append 'cmdline' --load Image
>
> dtb_set_property: fdt_add_subnode failed: <valid offset/length>
> kexec: Set device tree bootargs failed.
>
> This happens because currently we check the return value of
> 'fdt_add_subnode()' function call in 'dt-ops.c' incorrectly:
>
> result = fdt_add_subnode(new_dtb, nodeoffset, node);
> if (result) {
> dbgprintf("%s: fdt_add_subnode failed: %s\n", _func__,
> fdt_strerror(result));
> goto on_error;
> }
>
> As we can see in 'fdt_rw.c', a positive return value from
> 'fdt_add_subnode()' function doesn't indicate an error.
>
> We can see that the Linux kernel (see 'drivers/firmware/efi/libstub/fdt.c'
> for example) also checks the 'fdt_add_subnode()' function against negative
> return values for errors. See an example below from 'update_fdt()' function in
> 'drivers/firmware/efi/libstub/fdt.c':
>
> node = fdt_add_subnode(fdt, 0, "chosen");
> if (node < 0) {
> status = node;
> <..snip..>
> goto fdt_set_fail;
> }
>
> This patch fixes the same in 'kexec-tools'.
Looks good.
Thank you.
-Takahiro Akashi
> [1]. http://lists.infradead.org/pipermail/kexec/2018-October/021746.html
>
> Cc: Simon Horman <horms@xxxxxxxxxxxx>
> Cc: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
> Reported-by: Vicente Bergas <vicencb@xxxxxxxxx>
> Signed-off-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx>
> ---
> kexec/dt-ops.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kexec/dt-ops.c b/kexec/dt-ops.c
> index 915dbf55afd2..f15174c3c74e 100644
> --- a/kexec/dt-ops.c
> +++ b/kexec/dt-ops.c
> @@ -84,7 +84,7 @@ int dtb_set_property(char **dtb, off_t *dtb_size, const char *node,
> if (nodeoffset == -FDT_ERR_NOTFOUND) {
> result = fdt_add_subnode(new_dtb, nodeoffset, node);
>
> - if (result) {
> + if (result < 0) {
> dbgprintf("%s: fdt_add_subnode failed: %s\n", __func__,
> fdt_strerror(result));
> goto on_error;
> --
> 2.7.4
>
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