lkml.org 
[lkml]   [2022]   [Aug]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] ALSA: control: Fix an out-of-bounds bug in get_ctl_id_hash()
Date
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(-)

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;
--
2.25.1
\
 
 \ /
  Last update: 2022-08-24 10:17    [W:0.085 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site