Re: [PATCH] ALSA: hda: Fix connection list comparison in proc output

[Takashi Iwai]

On Tue, 18 Aug 2026 10:38:08 +0200,
raoxu wrote:
> 
> From: Xu Rao <raoxu@xxxxxxxxxxxxx>
> 
> print_conn_list() compares the raw hardware connection list with the
> connection list cached by the HDA driver.  When they differ, it prints an
> additional "In-driver Connection" line so that /proc/asound/card*/codec#*
> shows the topology actually used by the driver.
> 
> The comparison currently passes conn_len directly to memcmp().  However,
> conn_len is a number of connection-list entries, while memcmp() expects a
> size in bytes.  Both list and conn are arrays of hda_nid_t, which is u16,
> so only half of the connection data is compared.
> 
> For example, for two-entry lists such as:
> 
>   hardware: 0x0c 0x0d
>   cached:   0x0c 0x0e
> 
> conn_len is 2, and the current comparison checks only the first hda_nid_t.
> The lists are therefore incorrectly treated as identical even though the
> second connection differs.
> 
> This can happen legitimately when codec fixups replace a cached connection
> list with snd_hda_override_conn_list().  The codec routing used by the
> driver is not affected, but the proc output can hide the overridden
> driver-visible routing and provide misleading topology information during
> codec debugging.
> 
> Convert the entry count to a byte size so that memcmp() covers the
> complete connection list.
> 
> Fixes: 8b2c7a5c404d ("ALSA: hda - Add In-driver connection info")
> Signed-off-by: Xu Rao <raoxu@xxxxxxxxxxxxx>

Thanks, applied now.


Takashi