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The current implementation of ALSA control API fully relies on the callbacks of each driver, and there is no verification of the values passed via API. This patch is an attempt to improve the situation slightly by adding the validation code for the values stored via info and get callbacks. The patch adds a new kconfig, CONFIG_SND_CTL_VALIDATION. It depends on CONFIG_SND_DEBUG and off as default since the validation would require a slight overhead including the additional call of info callback at each get callback invocation. When this config is enabled, the values stored by each info callback invocation are verified, namely: - Whether the info type is valid - Whether the number of enum items is non-zero - Whether the given info count is within the allowed boundary Similarly, the values stored at each get callback are verified as well: - Whether the values are within the given range - Whether the values are aligned with the given step - Whether any further changes are seen in the data array over the given info count The last point helps identifying a possibly invalid data type access, typically a case where the info callback declares the type being SNDRV_CTL_ELEM_TYPE_ENUMERATED while the get/put callbacks store the values in value.integer.value[] array. When a validation fails, the ALSA core logs an error message including the device and the control ID, and the API call also returns an error. So, with the new validation turned on, the driver behavior difference may be visible on user-space, too -- it's intentional, though, so that we can catch an error more clearly. The patch also introduces a new ctl access type, SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK. A driver may pass this flag with other access bits to indicate that the ctl element won't be verified. It's useful when a driver code is specially written to access the data greater than info->count size by some reason. For example, this flag is actually set now in HD-audio HDMI codec driver which needs to clear the data array in the case of the disconnected monitor. Also, the PCM channel-map helper code is slightly modified to avoid the false-positive hit by this validation code, too. Link: https://lore.kernel.org/r/20200104083556.27789-1-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
198 lines
5.0 KiB
Plaintext
198 lines
5.0 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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# ALSA soundcard-configuration
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config SND_TIMER
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tristate
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config SND_PCM
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tristate
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select SND_TIMER if SND_PCM_TIMER
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config SND_PCM_ELD
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bool
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config SND_PCM_IEC958
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bool
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config SND_DMAENGINE_PCM
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tristate
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config SND_HWDEP
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tristate
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config SND_SEQ_DEVICE
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tristate
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config SND_RAWMIDI
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tristate
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select SND_SEQ_DEVICE if SND_SEQUENCER != n
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config SND_COMPRESS_OFFLOAD
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tristate
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config SND_JACK
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bool
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# enable input device support in jack layer
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config SND_JACK_INPUT_DEV
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bool
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depends on SND_JACK
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default y if INPUT=y || INPUT=SND
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config SND_OSSEMUL
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bool "Enable OSS Emulation"
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select SOUND_OSS_CORE
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help
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This option enables the build of OSS emulation layer.
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config SND_MIXER_OSS
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tristate "OSS Mixer API"
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depends on SND_OSSEMUL
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help
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To enable OSS mixer API emulation (/dev/mixer*), say Y here
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and read <file:Documentation/sound/designs/oss-emulation.rst>.
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Many programs still use the OSS API, so say Y.
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To compile this driver as a module, choose M here: the module
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will be called snd-mixer-oss.
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config SND_PCM_OSS
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tristate "OSS PCM (digital audio) API"
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depends on SND_OSSEMUL
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select SND_PCM
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help
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To enable OSS digital audio (PCM) emulation (/dev/dsp*), say Y
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here and read <file:Documentation/sound/designs/oss-emulation.rst>.
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Many programs still use the OSS API, so say Y.
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To compile this driver as a module, choose M here: the module
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will be called snd-pcm-oss.
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config SND_PCM_OSS_PLUGINS
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bool "OSS PCM (digital audio) API - Include plugin system"
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depends on SND_PCM_OSS
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default y
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help
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If you disable this option, the ALSA's OSS PCM API will not
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support conversion of channels, formats and rates. It will
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behave like most of new OSS/Free drivers in 2.4/2.6 kernels.
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config SND_PCM_TIMER
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bool "PCM timer interface" if EXPERT
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default y
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help
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If you disable this option, pcm timer will be unavailable, so
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those stubs that use pcm timer (e.g. dmix, dsnoop & co) may work
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incorrectlly.
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For some embedded devices, we may disable it to reduce memory
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footprint, about 20KB on x86_64 platform.
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config SND_HRTIMER
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tristate "HR-timer backend support"
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depends on HIGH_RES_TIMERS
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select SND_TIMER
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help
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Say Y here to enable HR-timer backend for ALSA timer. ALSA uses
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the hrtimer as a precise timing source. The ALSA sequencer code
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also can use this timing source.
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To compile this driver as a module, choose M here: the module
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will be called snd-hrtimer.
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config SND_DYNAMIC_MINORS
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bool "Dynamic device file minor numbers"
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help
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If you say Y here, the minor numbers of ALSA device files in
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/dev/snd/ are allocated dynamically. This allows you to have
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more than 8 sound cards, but requires a dynamic device file
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system like udev.
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If you are unsure about this, say N here.
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config SND_MAX_CARDS
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int "Max number of sound cards"
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range 4 256
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default 32
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depends on SND_DYNAMIC_MINORS
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help
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Specify the max number of sound cards that can be assigned
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on a single machine.
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config SND_SUPPORT_OLD_API
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bool "Support old ALSA API"
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default y
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help
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Say Y here to support the obsolete ALSA PCM API (ver.0.9.0 rc3
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or older).
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config SND_PROC_FS
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bool "Sound Proc FS Support" if EXPERT
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depends on PROC_FS
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default y
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help
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Say 'N' to disable Sound proc FS, which may reduce code size about
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9KB on x86_64 platform.
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If unsure say Y.
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config SND_VERBOSE_PROCFS
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bool "Verbose procfs contents"
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depends on SND_PROC_FS
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default y
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help
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Say Y here to include code for verbose procfs contents (provides
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useful information to developers when a problem occurs). On the
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other side, it makes the ALSA subsystem larger.
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config SND_VERBOSE_PRINTK
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bool "Verbose printk"
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help
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Say Y here to enable verbose log messages. These messages
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will help to identify source file and position containing
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printed messages.
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You don't need this unless you're debugging ALSA.
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config SND_DEBUG
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bool "Debug"
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help
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Say Y here to enable ALSA debug code.
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config SND_DEBUG_VERBOSE
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bool "More verbose debug"
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depends on SND_DEBUG
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help
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Say Y here to enable extra-verbose debugging messages.
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Let me repeat: it enables EXTRA-VERBOSE DEBUGGING messages.
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So, say Y only if you are ready to be annoyed.
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config SND_PCM_XRUN_DEBUG
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bool "Enable PCM ring buffer overrun/underrun debugging"
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default n
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depends on SND_DEBUG && SND_VERBOSE_PROCFS
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help
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Say Y to enable the PCM ring buffer overrun/underrun debugging.
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It is usually not required, but if you have trouble with
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sound clicking when system is loaded, it may help to determine
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the process or driver which causes the scheduling gaps.
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config SND_CTL_VALIDATION
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bool "Perform sanity-checks for each control element access"
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depends on SND_DEBUG
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help
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Say Y to enable the additional validation of each control element
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access, including sanity-checks like whether the values returned
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from the driver are in the proper ranges or the check of the invalid
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access at out-of-array areas.
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config SND_VMASTER
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bool
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config SND_DMA_SGBUF
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def_bool y
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depends on X86
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source "sound/core/seq/Kconfig"
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