Re: [PATCH v2 04/14] Running with --enable-ubsan leads to a qtest failure

[Akihiko Odaki <akihiko.odaki@daynix.com>]

I think the subject should tell what this patch does and perhaps the 
underlying problem it solves instead of the symptom. It may be nice to 
have a prefix "tests/qtest/libqos/igb:" to comply the convention.

On 2025/05/06 21:57, Alex Bennée wrote:
> From: Nabih Estefan <nabihestefan@google.com>
> 
>    ../tests/qtest/libqos/igb.c:106:5: runtime error: load of misaligned address 0x562040be8e33 for type 'uint32_t', which requires 4 byte alignment
> 
> Instead of straight casting the uint8_t array, we use use ldl_le_p and
> lduw_l_p to assure alignment is correct against uint32_t and uint16_t.

It does not assure an alignment is correct but instead performs an 
unaligned access.

> 
> Signed-off-by: Nabih Estefan <nabihestefan@google.com>
> Reviewed-by: Laurent Vivier <lvivier@redhat.com>
> Tested-by: Laurent Vivier <lvivier@redhat.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Message-Id: <20250429155621.2028198-1-nabihestefan@google.com>
> [AJB: fix commit message, remove unneeded casts]
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---
>   tests/qtest/libqos/igb.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/qtest/libqos/igb.c b/tests/qtest/libqos/igb.c
> index f40c4ec4cd..7df9272069 100644
> --- a/tests/qtest/libqos/igb.c
> +++ b/tests/qtest/libqos/igb.c
> @@ -104,10 +104,10 @@ static void igb_pci_start_hw(QOSGraphObject *obj)
>       e1000e_macreg_write(&d->e1000e, E1000_RDT(0), 0);
>       e1000e_macreg_write(&d->e1000e, E1000_RDH(0), 0);
>       e1000e_macreg_write(&d->e1000e, E1000_RA,
> -                        le32_to_cpu(*(uint32_t *)address));
> +                        ldl_le_p(address));
>       e1000e_macreg_write(&d->e1000e, E1000_RA + 4,
>                           E1000_RAH_AV | E1000_RAH_POOL_1 |
> -                        le16_to_cpu(*(uint16_t *)(address + 4)));
> +                        lduw_le_p((address + 4)));

This line has are extra parentheses.

>   
>       /* Set supported receive descriptor mode */
>       e1000e_macreg_write(&d->e1000e,