| Message ID | 20220824081654.3767739-1-zheyuma97@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 6ab55ec0a938c7f943a4edba3d6514f775983887 |
| Headers | show |
| Series | ALSA: control: Fix an out-of-bounds bug in get_ctl_id_hash() | expand |
On Wed, 24 Aug 2022 10:16:54 +0200, Zheyu Ma wrote: > > 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 <zheyuma97@gmail.com> Thanks, applied now. Takashi
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;
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 <zheyuma97@gmail.com> --- sound/core/control.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)