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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: c27e1efb61 ("ALSA: control: Use xarray for faster lookups")
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Link: https://lore.kernel.org/r/20220824081654.3767739-1-zheyuma97@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Zheyu Ma 2022-08-24 16:16:54 +08:00 committed by Takashi Iwai
parent 2e6481a3f3
commit 6ab55ec0a9
1 changed files with 3 additions and 3 deletions
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6
sound/core/control.c
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@ -385,14 +385,14 @@ static bool elem_id_matches(const struct snd_kcontrol *kctl,
#define MULTIPLIER 37 #define MULTIPLIER 37
static unsigned long get_ctl_id_hash(const struct snd_ctl_elem_id *id) static unsigned long get_ctl_id_hash(const struct snd_ctl_elem_id *id)
{ {
int i;
unsigned long h; unsigned long h;
const unsigned char *p;
h = id->iface; h = id->iface;
h = MULTIPLIER * h + id->device; h = MULTIPLIER * h + id->device;
h = MULTIPLIER * h + id->subdevice; h = MULTIPLIER * h + id->subdevice;
for (p = id->name; *p; p++) for (i = 0; id->name[i] && i < SNDRV_CTL_ELEM_ID_NAME_MAXLEN; i++)
h = MULTIPLIER * h + *p; h = MULTIPLIER * h + id->name[i];
h = MULTIPLIER * h + id->index; h = MULTIPLIER * h + id->index;
h &= LONG_MAX; h &= LONG_MAX;
return h; return h;