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Re: [PATCH] x86/EFI: fix padding of EDD strings
- To: Anandu Padinhare <Anandu.Padinhare@xxxxxxxxxxxxxx>
- From: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
- Date: Mon, 9 Nov 2026 15:52:17 +0100
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On Thu, Nov 05, 2026 at 09:10:28AM +0000, Anandu Padinhare wrote:
> edd_put_string() decrements n in its copy loop condition even when the
> loop terminates because the end of the source string was reached. The
> padding loop then writes one space too few, leaving the final byte of
> the field untouched (zero, as boot_edd_info[] lives in .bss). On an EFI
> boot this yields e.g. a host bus type of "PCI\0" and an interface type
> of "ATAPI \0", whereas BIOSes space-pad these fields (SeaBIOS reports
> "PCI " and "ATA ").
>
> Furthermore, if the string exactly filled the field, n would wrap to
> SIZE_MAX after the copy loop and the padding loop would write past the
> end of the field. No caller currently passes such a string.
>
> Only decrement n when a character was actually copied. While touching
> the function, also correct its indentation.
>
> Fixes: 51f03ec421fb ("x86-64/EFI: construct EDD data from device path
> protocol information")
> Assisted-by: Claude
> Signed-off-by: Anandu Padinhare <Anandu.Padinhare@xxxxxxxxxxxxxx>
Reviewed-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
--
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
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