Re: [PATCH] x86/EFI: fix padding of EDD strings

["Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>]

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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@electrifex.com>

Reviewed-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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