[PATCH v3] mkimage: Default to 8-byte alignment for DTBs added via -b argument

[Tom Rini]

On Tue, Jan 27, 2026 at 01:36:59AM +0100, Marek Vasut wrote:
> On 1/26/26 11:58 PM, Tom Rini wrote:
> 
> > > > 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.
> 
> Which is wrong, and trivial to fix -- check the "len" that is already
> provided to you by fdt_getprop() and make sure it is exactly length of
> FIT_TYPE_PROP before doing the strcmp() . Then you should be safe.
> 
> > > The other thing that can go wrong is if we get something like
> > > "flat_dt\0extra data" we will match.
> 
> This I did not consider. So maybe what needs to be done is compare the
> length and then memcmp() instead of strcmp().
> 
> > > 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.
> 
> fdt_string_eq_() seems like the best fit, yes , nice.

Bad news, fdt_string_eq_() is an internal call in libfdt. Good news,
fdt_getprop() makes use of it via its eventual call chain. Which I think
gets back to what I said earlier, libfdt is doing the input sanitization
for us, or so many other places are more useful to exploit?

-- 
Tom
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 228 bytes
Desc: not available
URL: <https://lists.denx.de/pipermail/u-boot/attachments/20260127/994c3423/attachment.sig>