[PATCH] ALSA: control: do not access controls without possession of r_w lock
we should not access any of its memory when we don't ensure possession of a read/write lock. Otherwise we risk a use after free access, which allows local users to cause a denial of service and obtain sensitive information from kernel memory.
Signed-off-by: Ma Ke make_ruc2021@163.com --- sound/core/control.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/sound/core/control.c b/sound/core/control.c index 59c8658966d4..98782cc68ee1 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -590,7 +590,8 @@ static int __snd_ctl_remove(struct snd_card *card, remove_hash_entries(card, kcontrol);
card->controls_count -= kcontrol->count; - for (idx = 0; idx < kcontrol->count; idx++) + count = kcontrol->count; + for (idx = 0; idx < count; idx++) snd_ctl_notify_one(card, SNDRV_CTL_EVENT_MASK_REMOVE, kcontrol, idx); snd_ctl_free_one(kcontrol); return 0;
On Tue, 12 Sep 2023 10:45:30 +0200, Ma Ke wrote:
we should not access any of its memory when we don't ensure possession of a read/write lock. Otherwise we risk a use after free access, which allows local users to cause a denial of service and obtain sensitive information from kernel memory.
This function is called always under card->controls_rwsem. So it should be OK as is.
thanks,
Takashi
Signed-off-by: Ma Ke make_ruc2021@163.com
sound/core/control.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/sound/core/control.c b/sound/core/control.c index 59c8658966d4..98782cc68ee1 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -590,7 +590,8 @@ static int __snd_ctl_remove(struct snd_card *card, remove_hash_entries(card, kcontrol);
card->controls_count -= kcontrol->count;
- for (idx = 0; idx < kcontrol->count; idx++)
- count = kcontrol->count;
- for (idx = 0; idx < count; idx++) snd_ctl_notify_one(card, SNDRV_CTL_EVENT_MASK_REMOVE, kcontrol, idx); snd_ctl_free_one(kcontrol); return 0;
-- 2.37.2
Hi Ma,
kernel test robot noticed the following build errors:
[auto build test ERROR on tiwai-sound/for-next] [also build test ERROR on tiwai-sound/for-linus linus/master v6.6-rc1 next-20230912] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Ma-Ke/ALSA-control-do-not-acc... base: https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git for-next patch link: https://lore.kernel.org/r/20230912084530.3307329-1-make_ruc2021%40163.com patch subject: [PATCH] ALSA: control: do not access controls without possession of r_w lock config: arm-randconfig-r032-20230913 (https://download.01.org/0day-ci/archive/20230913/202309130328.UdCL3yzt-lkp@i...) compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230913/202309130328.UdCL3yzt-lkp@i...)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot lkp@intel.com | Closes: https://lore.kernel.org/oe-kbuild-all/202309130328.UdCL3yzt-lkp@intel.com/
All errors (new ones prefixed by >>):
sound/core/control.c:593:2: error: use of undeclared identifier 'count'
593 | count = kcontrol->count; | ^ sound/core/control.c:594:22: error: use of undeclared identifier 'count' 594 | for (idx = 0; idx < count; idx++) | ^ 2 errors generated.
vim +/count +593 sound/core/control.c
576 577 static int __snd_ctl_remove(struct snd_card *card, 578 struct snd_kcontrol *kcontrol, 579 bool remove_hash) 580 { 581 unsigned int idx; 582 583 lockdep_assert_held_write(&card->controls_rwsem); 584 585 if (snd_BUG_ON(!card || !kcontrol)) 586 return -EINVAL; 587 list_del(&kcontrol->list); 588 589 if (remove_hash) 590 remove_hash_entries(card, kcontrol); 591 592 card->controls_count -= kcontrol->count;
593 count = kcontrol->count;
594 for (idx = 0; idx < count; idx++) 595 snd_ctl_notify_one(card, SNDRV_CTL_EVENT_MASK_REMOVE, kcontrol, idx); 596 snd_ctl_free_one(kcontrol); 597 return 0; 598 } 599
Hi Ma,
kernel test robot noticed the following build errors:
[auto build test ERROR on tiwai-sound/for-next] [also build test ERROR on tiwai-sound/for-linus linus/master v6.6-rc3 next-20230921] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Ma-Ke/ALSA-control-do-not-acc... base: https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git for-next patch link: https://lore.kernel.org/r/20230912084530.3307329-1-make_ruc2021%40163.com patch subject: [PATCH] ALSA: control: do not access controls without possession of r_w lock config: loongarch-defconfig (https://download.01.org/0day-ci/archive/20230925/202309251036.Yjiuc0Lq-lkp@i...) compiler: loongarch64-linux-gcc (GCC) 13.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230925/202309251036.Yjiuc0Lq-lkp@i...)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot lkp@intel.com | Closes: https://lore.kernel.org/oe-kbuild-all/202309251036.Yjiuc0Lq-lkp@intel.com/
All errors (new ones prefixed by >>):
sound/core/control.c: In function '__snd_ctl_remove':
sound/core/control.c:593:9: error: 'count' undeclared (first use in this function); did you mean 'd_count'?
593 | count = kcontrol->count; | ^~~~~ | d_count sound/core/control.c:593:9: note: each undeclared identifier is reported only once for each function it appears in
vim +593 sound/core/control.c
576 577 static int __snd_ctl_remove(struct snd_card *card, 578 struct snd_kcontrol *kcontrol, 579 bool remove_hash) 580 { 581 unsigned int idx; 582 583 lockdep_assert_held_write(&card->controls_rwsem); 584 585 if (snd_BUG_ON(!card || !kcontrol)) 586 return -EINVAL; 587 list_del(&kcontrol->list); 588 589 if (remove_hash) 590 remove_hash_entries(card, kcontrol); 591 592 card->controls_count -= kcontrol->count;
593 count = kcontrol->count;
594 for (idx = 0; idx < count; idx++) 595 snd_ctl_notify_one(card, SNDRV_CTL_EVENT_MASK_REMOVE, kcontrol, idx); 596 snd_ctl_free_one(kcontrol); 597 return 0; 598 } 599
participants (3)
-
kernel test robot -
Ma Ke -
Takashi Iwai