ALSA: control: Validate buf_len before strnlen() in snd_ctl_elem_init_enum_names()

Browse source

commit e0da8a8cac upstream.

snd_ctl_elem_init_enum_names() advances pointer p through the names
buffer while decrementing buf_len. If buf_len reaches zero but items
remain, the next iteration calls strnlen(p, 0).

While strnlen(p, 0) returns 0 and would hit the existing name_len == 0
error path, CONFIG_FORTIFY_SOURCE's fortified strnlen() first checks
maxlen against __builtin_dynamic_object_size(). When Clang loses track
of p's object size inside the loop, this triggers a BRK exception panic
before the return value is examined.

Add a buf_len == 0 guard at the loop entry to prevent calling fortified
strnlen() on an exhausted buffer.

Found by kernel fuzz testing through Xiaomi Smartphone.

Fixes: 8d448162bd ("ALSA: control: add support for ENUMERATED user space controls")
Cc: stable@vger.kernel.org
Signed-off-by: Ziqing Chen <chenziqing@xiaomi.com>
Link: https://patch.msgid.link/20260414132437.261304-1-chenziqing@xiaomi.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Ziqing Chen 2026-04-14 21:24:37 +08:00 • committed by Greg Kroah-Hartman

parent 1d7f07df45

commit bfcbb4994d

1 changed files with 4 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

4

sound/core/control.c

View file