On 1/26/26 16:50, Marek Vasut wrote:
> On 1/26/26 6:38 PM, Sean Anderson wrote:
>> On 1/23/26 05:51, Marek Vasut wrote:
>>> On 1/23/26 11:40 AM, Anshul Dalal wrote:
>>>> Hi Marek,
>>>>
>>>> On Fri Jan 23, 2026 at 3:57 PM IST, Marek Vasut wrote:
>>>>> On 1/23/26 4:32 AM, Beleswar Prasad Padhi wrote:
>>>>>>
>>>>>> On 23/01/26 00:33, Marek Vasut wrote:
>>>>>>> On 1/22/26 6:45 PM, Tom Rini wrote:
>>>>>>>> On Thu, Jan 22, 2026 at 10:52:47PM +0530, Beleswar Padhi wrote:
>>>>>>>>
>>>>>>>>> When CONFIG_SPL_MULTI_DTB_FIT is enabled, multiple device trees are
>>>>>>>>> packed inside the multidtb.fit FIT image. While the individual DTBs
>>>>>>>>> and the FIT image start address are 8-byte aligned, the DTBs embedded
>>>>>>>>> within the FIT image are not guaranteed to maintain 8-byte alignment.
>>>>>>>>>
>>>>>>>>> This misalignment causes -FDT_ERR_ALIGNMENT failure in
>>>>>>>>> setup_multi_dtb_fit() when locating the next available DTB within the
>>>>>>>>> FIT blob and setting gd->fdt_blob, because of the recent libfdt
>>>>>>>>> hardening since commit 0535e46d55d7 ("scripts/dtc: Update to upstream
>>>>>>>>> version v1.7.2-35-g52f07dcca47c")
>>>>>>>>>
>>>>>>>>> The mkimage tool already supports enforcing this alignment via the -B
>>>>>>>>> option, but users would have to specify it explicitly. This change
>>>>>>>>> makes 8-byte alignment the default when using -b.
>>>>>>>>>
>>>>>>>>> Reported-by: Anshul Dalal <[email protected]>
>>>>>>>>> Closes:
>>>>>>>>> https://cas5-0-urlprotect.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%2f%2flore.kernel.org%2fu%2dboot%2fDFJ950O0QM0D.380U0N16ZO19E%40ti.com&umid=003810bd-b0e0-4a71-9348-75ffbe5cbae5&rct=1769167692&auth=d807158c60b7d2502abde8a2fc01f40662980862-3859cf23dac8d65722a0a9ed4c40c98c98a297de
>>>>>>>>> Fixes: 0535e46d55d7 ("scripts/dtc: Update to upstream version
>>>>>>>>> v1.7.2-35-g52f07dcca47c")
>>>>>>>>> Signed-off-by: Beleswar Padhi <[email protected]>
>>>>>>>>
>>>>>>>> Tested-by: Tom Rini <[email protected]>
>>>>>>> Doesn't this enable 8-byte alignment for everything in case a DT is
>>>>>>> specified on mkimage command line ? That doesn't seem right ?
>>>>>>>
>>>>>>> If I do mkimage -f auto -b ...dtb ... , then I only want the DTB to be
>>>>>>> 8-byte aligned, all the other blobs can be 4 byte aligned just fine .
>>>>>>
>>>>>>
>>>>>> All the mkimage flags are parsed at once and populated in the params
>>>>>> data structure in one shot in the code. There is no separation of code
>>>>>> specifically for generating a FIT for a DTB vs for anything else.
>>>>>
>>>>> That does not seem to be true ?
>>>>>
>>>>> $ git grep -p '\<bl_len\>' tools/
>>>>> tools/fit_image.c=static int fit_extract_data(struct image_tool_params
>>>>> *params, const char *fname)
>>>>> tools/fit_image.c: align_size = params->bl_len ? params->bl_len : 4;
>>>>> ...
>>>>>
>>>>> So something like that may work ?
>>>>>
>>>>> "
>>>>> diff --git a/tools/fit_image.c b/tools/fit_image.c
>>>>> index 0306333141e..0c606ba4cc3 100644
>>>>> --- a/tools/fit_image.c
>>>>> +++ b/tools/fit_image.c
>>>>> @@ -642,9 +642,15 @@ static int fit_extract_data(struct
>>>>> image_tool_params *params, const char *fname)
>>>>> for (node = fdt_first_subnode(fdt, images);
>>>>> node >= 0;
>>>>> node = fdt_next_subnode(fdt, node)) {
>>>>> - const char *data;
>>>>> + const char *data, *type;
>>>>> int len;
>>>>>
>>>>> + if (align_size < 8) {
>>>>> + type = fdt_getprop(fdt, node, FIT_TYPE_PROP,
>>>>> &len);
>>>>> + if (type && !strcmp(type, "flat_dt"))
>>>>> + align_size = 8;
>>>>> + }
>>>>> +
>>>>> data = fdt_getprop(fdt, node, FIT_DATA_PROP, &len);
>>>>> if (!data)
>>>>> continue;
>>>>> "
>>>>>
>>>>
>>>> I just ran a quick test with this diff and it seems to fix the issue for
>>>> us. If it's okay can we take the change as is.
>>> I think the strcmp needs to be some strncmp and check the 'len' too.
>>>
>>> Let's see what others think.
>>
>> strcmp is fine when one of the strings is a constant
>>
>> If type is shorter than "flat_dt" then there is no risk of overflow.
>
> What exact data would you be comparing here , the constant and something read
> from possibly past the user supplied "type" buffer ?
>
> Some validation of "len" has to be done before it is fed into strcmp() here.
Well if you are concerned about lacking a nul-terminator then we will
read at most 8 bytes beyond the string.
The other thing that can go wrong is if we get something like
"flat_dt\0extra data" we will match.
Surprisingly the closest we have to this construct is fdt_string_eq_. I
suppose this is because most strings in U-Boot are guaranteed to be
nul-terminated.
--Sean
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