From 6ab55ec0a938c7f943a4edba3d6514f775983887 Mon Sep 17 00:00:00 2001 From: Zheyu Ma Date: Wed, 24 Aug 2022 16:16:54 +0800 Subject: [PATCH] ALSA: control: Fix an out-of-bounds bug in get_ctl_id_hash() Since the user can control the arguments provided to the kernel by the ioctl() system call, an out-of-bounds bug occurs when the 'id->name' provided by the user does not end with '\0'. The following log can reveal it: [ 10.002313] BUG: KASAN: stack-out-of-bounds in snd_ctl_find_id+0x36c/0x3a0 [ 10.002895] Read of size 1 at addr ffff888109f5fe28 by task snd/439 [ 10.004934] Call Trace: [ 10.007140] snd_ctl_find_id+0x36c/0x3a0 [ 10.007489] snd_ctl_ioctl+0x6cf/0x10e0 Fix this by checking the bound of 'id->name' in the loop. Fixes: c27e1efb61c5 ("ALSA: control: Use xarray for faster lookups") Signed-off-by: Zheyu Ma Link: https://lore.kernel.org/r/20220824081654.3767739-1-zheyuma97@gmail.com Signed-off-by: Takashi Iwai --- sound/core/control.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/sound/core/control.c b/sound/core/control.c index f3e893715369..e8fc4c511e5f 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -385,14 +385,14 @@ static bool elem_id_matches(const struct snd_kcontrol *kctl, #define MULTIPLIER 37 static unsigned long get_ctl_id_hash(const struct snd_ctl_elem_id *id) { + int i; unsigned long h; - const unsigned char *p; h = id->iface; h = MULTIPLIER * h + id->device; h = MULTIPLIER * h + id->subdevice; - for (p = id->name; *p; p++) - h = MULTIPLIER * h + *p; + for (i = 0; id->name[i] && i < SNDRV_CTL_ELEM_ID_NAME_MAXLEN; i++) + h = MULTIPLIER * h + id->name[i]; h = MULTIPLIER * h + id->index; h &= LONG_MAX; return h;