Files
linux/sound/hda
Xu Rao c139e7e44f ALSA: hda: Fix connection list comparison in proc output
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: 8b2c7a5c40 ("ALSA: hda - Add In-driver connection info")
Signed-off-by: Xu Rao <raoxu@uniontech.com>
Link: https://patch.msgid.link/7B802A4E225CC808+20260818083808.2735120-1-raoxu@uniontech.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2026-08-18 11:40:38 +02:00
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