| Message ID | 20230210051447.never.204-kees@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ASoC: Intel: Skylake: Replace 1-element array with flex-array | expand |
On 10/02/2023 07:14, Kees Cook wrote: > The kernel is globally removing the ambiguous 0-length and 1-element > arrays in favor of flexible arrays, so that we can gain both compile-time > and run-time array bounds checking[1]. In this instance, struct > skl_cpr_cfg contains struct skl_cpr_gtw_cfg, which defined "config_data" > as a 1-element array. > > Normally when switching from a 1-element array to a flex-array, any > related size calculations must be adjusted too. However, it seems the > original code was over-allocating space, since 1 extra u32 would be > included by the sizeof(): > > param_size = sizeof(struct skl_cpr_cfg); > param_size += mconfig->formats_config[SKL_PARAM_INIT].caps_size; > > But the copy uses caps_size bytes, and cap_size / 4 (i.e. sizeof(u32)) > for the length tracking: > > memcpy(cpr_mconfig->gtw_cfg.config_data, > mconfig->formats_config[SKL_PARAM_INIT].caps, > mconfig->formats_config[SKL_PARAM_INIT].caps_size); > > cpr_mconfig->gtw_cfg.config_length = > (mconfig->formats_config[SKL_PARAM_INIT].caps_size) / 4; > > Therefore, no size calculations need adjusting. Change the struct > skl_cpr_gtw_cfg config_data member to be a true flexible array, which > also fixes the over-allocation, and silences this memcpy run-time false > positive: > > memcpy: detected field-spanning write (size 100) of single field "cpr_mconfig->gtw_cfg.config_data" at sound/soc/intel/skylake/skl-messages.c:554 (size 4) > > [1] For lots of details, see both: > https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays > https://people.kernel.org/kees/bounded-flexible-arrays-in-c Reviewed-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com> > > Reported-by: Sasa Ostrouska <casaxa@gmail.com> > Link: https://lore.kernel.org/all/CALFERdwvq5day_sbDfiUsMSZCQu9HG8-SBpOZDNPeMdZGog6XA@mail.gmail.com/ > Cc: Cezary Rojewski <cezary.rojewski@intel.com> > Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> > Cc: Liam Girdwood <liam.r.girdwood@linux.intel.com> > Cc: Peter Ujfalusi <peter.ujfalusi@linux.intel.com> > Cc: Bard Liao <yung-chuan.liao@linux.intel.com> > Cc: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> > Cc: Kai Vehmanen <kai.vehmanen@linux.intel.com> > Cc: Mark Brown <broonie@kernel.org> > Cc: Jaroslav Kysela <perex@perex.cz> > Cc: Takashi Iwai <tiwai@suse.com> > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > Cc: "Amadeusz Sławiński" <amadeuszx.slawinski@linux.intel.com> > Cc: alsa-devel@alsa-project.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > sound/soc/intel/skylake/skl-topology.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/sound/soc/intel/skylake/skl-topology.h b/sound/soc/intel/skylake/skl-topology.h > index 6db0fd7bad49..ad94f8020c27 100644 > --- a/sound/soc/intel/skylake/skl-topology.h > +++ b/sound/soc/intel/skylake/skl-topology.h > @@ -115,7 +115,7 @@ struct skl_cpr_gtw_cfg { > u32 dma_buffer_size; > u32 config_length; > /* not mandatory; required only for DMIC/I2S */ > - u32 config_data[1]; > + u32 config_data[]; > } __packed; > > struct skl_dma_control {
On 2/10/2023 6:14 AM, Kees Cook wrote: > The kernel is globally removing the ambiguous 0-length and 1-element > arrays in favor of flexible arrays, so that we can gain both compile-time > and run-time array bounds checking[1]. In this instance, struct > skl_cpr_cfg contains struct skl_cpr_gtw_cfg, which defined "config_data" > as a 1-element array. > > Normally when switching from a 1-element array to a flex-array, any > related size calculations must be adjusted too. However, it seems the > original code was over-allocating space, since 1 extra u32 would be > included by the sizeof(): > > param_size = sizeof(struct skl_cpr_cfg); > param_size += mconfig->formats_config[SKL_PARAM_INIT].caps_size; > > But the copy uses caps_size bytes, and cap_size / 4 (i.e. sizeof(u32)) > for the length tracking: > > memcpy(cpr_mconfig->gtw_cfg.config_data, > mconfig->formats_config[SKL_PARAM_INIT].caps, > mconfig->formats_config[SKL_PARAM_INIT].caps_size); > > cpr_mconfig->gtw_cfg.config_length = > (mconfig->formats_config[SKL_PARAM_INIT].caps_size) / 4; > > Therefore, no size calculations need adjusting. Change the struct > skl_cpr_gtw_cfg config_data member to be a true flexible array, which > also fixes the over-allocation, and silences this memcpy run-time false > positive: > > memcpy: detected field-spanning write (size 100) of single field "cpr_mconfig->gtw_cfg.config_data" at sound/soc/intel/skylake/skl-messages.c:554 (size 4) > > [1] For lots of details, see both: > https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays > https://people.kernel.org/kees/bounded-flexible-arrays-in-c > > Reported-by: Sasa Ostrouska <casaxa@gmail.com> > Link: https://lore.kernel.org/all/CALFERdwvq5day_sbDfiUsMSZCQu9HG8-SBpOZDNPeMdZGog6XA@mail.gmail.com/ > Cc: Cezary Rojewski <cezary.rojewski@intel.com> > Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> > Cc: Liam Girdwood <liam.r.girdwood@linux.intel.com> > Cc: Peter Ujfalusi <peter.ujfalusi@linux.intel.com> > Cc: Bard Liao <yung-chuan.liao@linux.intel.com> > Cc: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> > Cc: Kai Vehmanen <kai.vehmanen@linux.intel.com> > Cc: Mark Brown <broonie@kernel.org> > Cc: Jaroslav Kysela <perex@perex.cz> > Cc: Takashi Iwai <tiwai@suse.com> > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > Cc: "Amadeusz Sławiński" <amadeuszx.slawinski@linux.intel.com> > Cc: alsa-devel@alsa-project.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > sound/soc/intel/skylake/skl-topology.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/sound/soc/intel/skylake/skl-topology.h b/sound/soc/intel/skylake/skl-topology.h > index 6db0fd7bad49..ad94f8020c27 100644 > --- a/sound/soc/intel/skylake/skl-topology.h > +++ b/sound/soc/intel/skylake/skl-topology.h > @@ -115,7 +115,7 @@ struct skl_cpr_gtw_cfg { > u32 dma_buffer_size; > u32 config_length; > /* not mandatory; required only for DMIC/I2S */ > - u32 config_data[1]; > + u32 config_data[]; > } __packed; > > struct skl_dma_control { This fails in our validation. Maybe we can use the union workaround, to leave the size as is? Following seems to work in manual test: diff --git a/sound/soc/intel/skylake/skl-topology.h b/sound/soc/intel/skylake/skl-topology.h index 6db0fd7bad49..ffbd2e60fede 100644 --- a/sound/soc/intel/skylake/skl-topology.h +++ b/sound/soc/intel/skylake/skl-topology.h @@ -115,7 +115,10 @@ struct skl_cpr_gtw_cfg { u32 dma_buffer_size; u32 config_length; /* not mandatory; required only for DMIC/I2S */ - u32 config_data[1]; + union { + u32 x; + u32 config_data[0]; + }; } __packed; struct skl_dma_control { I can also run it through validation to make sure if it is acceptable.
On Fri, Feb 10, 2023 at 02:10:56PM +0100, Amadeusz Sławiński wrote: > On 2/10/2023 6:14 AM, Kees Cook wrote: > > The kernel is globally removing the ambiguous 0-length and 1-element > > arrays in favor of flexible arrays, so that we can gain both compile-time > > and run-time array bounds checking[1]. In this instance, struct > > skl_cpr_cfg contains struct skl_cpr_gtw_cfg, which defined "config_data" > > as a 1-element array. > > > > Normally when switching from a 1-element array to a flex-array, any > > related size calculations must be adjusted too. However, it seems the > > original code was over-allocating space, since 1 extra u32 would be > > included by the sizeof(): > > > > param_size = sizeof(struct skl_cpr_cfg); > > param_size += mconfig->formats_config[SKL_PARAM_INIT].caps_size; > > > > But the copy uses caps_size bytes, and cap_size / 4 (i.e. sizeof(u32)) > > for the length tracking: > > > > memcpy(cpr_mconfig->gtw_cfg.config_data, > > mconfig->formats_config[SKL_PARAM_INIT].caps, > > mconfig->formats_config[SKL_PARAM_INIT].caps_size); > > > > cpr_mconfig->gtw_cfg.config_length = > > (mconfig->formats_config[SKL_PARAM_INIT].caps_size) / 4; > > > > Therefore, no size calculations need adjusting. Change the struct > > skl_cpr_gtw_cfg config_data member to be a true flexible array, which > > also fixes the over-allocation, and silences this memcpy run-time false > > positive: > > > > memcpy: detected field-spanning write (size 100) of single field "cpr_mconfig->gtw_cfg.config_data" at sound/soc/intel/skylake/skl-messages.c:554 (size 4) > > > > [1] For lots of details, see both: > > https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays > > https://people.kernel.org/kees/bounded-flexible-arrays-in-c > > > > Reported-by: Sasa Ostrouska <casaxa@gmail.com> > > Link: https://lore.kernel.org/all/CALFERdwvq5day_sbDfiUsMSZCQu9HG8-SBpOZDNPeMdZGog6XA@mail.gmail.com/ > > Cc: Cezary Rojewski <cezary.rojewski@intel.com> > > Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> > > Cc: Liam Girdwood <liam.r.girdwood@linux.intel.com> > > Cc: Peter Ujfalusi <peter.ujfalusi@linux.intel.com> > > Cc: Bard Liao <yung-chuan.liao@linux.intel.com> > > Cc: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> > > Cc: Kai Vehmanen <kai.vehmanen@linux.intel.com> > > Cc: Mark Brown <broonie@kernel.org> > > Cc: Jaroslav Kysela <perex@perex.cz> > > Cc: Takashi Iwai <tiwai@suse.com> > > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > > Cc: "Amadeusz Sławiński" <amadeuszx.slawinski@linux.intel.com> > > Cc: alsa-devel@alsa-project.org > > Signed-off-by: Kees Cook <keescook@chromium.org> > > --- > > sound/soc/intel/skylake/skl-topology.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/sound/soc/intel/skylake/skl-topology.h b/sound/soc/intel/skylake/skl-topology.h > > index 6db0fd7bad49..ad94f8020c27 100644 > > --- a/sound/soc/intel/skylake/skl-topology.h > > +++ b/sound/soc/intel/skylake/skl-topology.h > > @@ -115,7 +115,7 @@ struct skl_cpr_gtw_cfg { > > u32 dma_buffer_size; > > u32 config_length; > > /* not mandatory; required only for DMIC/I2S */ > > - u32 config_data[1]; > > + u32 config_data[]; > > } __packed; > > struct skl_dma_control { > > This fails in our validation. Ah, okay. Thanks for checking! > Maybe we can use the union workaround, to > leave the size as is? > > Following seems to work in manual test: > diff --git a/sound/soc/intel/skylake/skl-topology.h > b/sound/soc/intel/skylake/skl-topology.h > index 6db0fd7bad49..ffbd2e60fede 100644 > --- a/sound/soc/intel/skylake/skl-topology.h > +++ b/sound/soc/intel/skylake/skl-topology.h > @@ -115,7 +115,10 @@ struct skl_cpr_gtw_cfg { > u32 dma_buffer_size; > u32 config_length; > /* not mandatory; required only for DMIC/I2S */ > - u32 config_data[1]; > + union { > + u32 x; > + u32 config_data[0]; > + }; Yeah, that could work, though the last member would be: DECLARE_FLEX_ARRAY(u32, config_data); otherwise the array is 0 length (rather than a proper flex array). But before that, let me see if I can track down where the size is being used, in case we can avoid adding the padding.
On 2/10/2023 8:06 PM, Kees Cook wrote: > On Fri, Feb 10, 2023 at 02:10:56PM +0100, Amadeusz Sławiński wrote: >> On 2/10/2023 6:14 AM, Kees Cook wrote: >>> The kernel is globally removing the ambiguous 0-length and 1-element >>> arrays in favor of flexible arrays, so that we can gain both compile-time >>> and run-time array bounds checking[1]. In this instance, struct >>> skl_cpr_cfg contains struct skl_cpr_gtw_cfg, which defined "config_data" >>> as a 1-element array. >>> >>> Normally when switching from a 1-element array to a flex-array, any >>> related size calculations must be adjusted too. However, it seems the >>> original code was over-allocating space, since 1 extra u32 would be >>> included by the sizeof(): >>> >>> param_size = sizeof(struct skl_cpr_cfg); >>> param_size += mconfig->formats_config[SKL_PARAM_INIT].caps_size; >>> >>> But the copy uses caps_size bytes, and cap_size / 4 (i.e. sizeof(u32)) >>> for the length tracking: >>> >>> memcpy(cpr_mconfig->gtw_cfg.config_data, >>> mconfig->formats_config[SKL_PARAM_INIT].caps, >>> mconfig->formats_config[SKL_PARAM_INIT].caps_size); >>> >>> cpr_mconfig->gtw_cfg.config_length = >>> (mconfig->formats_config[SKL_PARAM_INIT].caps_size) / 4; >>> >>> Therefore, no size calculations need adjusting. Change the struct >>> skl_cpr_gtw_cfg config_data member to be a true flexible array, which >>> also fixes the over-allocation, and silences this memcpy run-time false >>> positive: >>> >>> memcpy: detected field-spanning write (size 100) of single field "cpr_mconfig->gtw_cfg.config_data" at sound/soc/intel/skylake/skl-messages.c:554 (size 4) >>> >>> [1] For lots of details, see both: >>> https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays >>> https://people.kernel.org/kees/bounded-flexible-arrays-in-c >>> >>> Reported-by: Sasa Ostrouska <casaxa@gmail.com> >>> Link: https://lore.kernel.org/all/CALFERdwvq5day_sbDfiUsMSZCQu9HG8-SBpOZDNPeMdZGog6XA@mail.gmail.com/ >>> Cc: Cezary Rojewski <cezary.rojewski@intel.com> >>> Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> >>> Cc: Liam Girdwood <liam.r.girdwood@linux.intel.com> >>> Cc: Peter Ujfalusi <peter.ujfalusi@linux.intel.com> >>> Cc: Bard Liao <yung-chuan.liao@linux.intel.com> >>> Cc: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> >>> Cc: Kai Vehmanen <kai.vehmanen@linux.intel.com> >>> Cc: Mark Brown <broonie@kernel.org> >>> Cc: Jaroslav Kysela <perex@perex.cz> >>> Cc: Takashi Iwai <tiwai@suse.com> >>> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> >>> Cc: "Amadeusz Sławiński" <amadeuszx.slawinski@linux.intel.com> >>> Cc: alsa-devel@alsa-project.org >>> Signed-off-by: Kees Cook <keescook@chromium.org> >>> --- >>> sound/soc/intel/skylake/skl-topology.h | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/sound/soc/intel/skylake/skl-topology.h b/sound/soc/intel/skylake/skl-topology.h >>> index 6db0fd7bad49..ad94f8020c27 100644 >>> --- a/sound/soc/intel/skylake/skl-topology.h >>> +++ b/sound/soc/intel/skylake/skl-topology.h >>> @@ -115,7 +115,7 @@ struct skl_cpr_gtw_cfg { >>> u32 dma_buffer_size; >>> u32 config_length; >>> /* not mandatory; required only for DMIC/I2S */ >>> - u32 config_data[1]; >>> + u32 config_data[]; >>> } __packed; >>> struct skl_dma_control { >> >> This fails in our validation. > > Ah, okay. Thanks for checking! > >> Maybe we can use the union workaround, to >> leave the size as is? >> >> Following seems to work in manual test: >> diff --git a/sound/soc/intel/skylake/skl-topology.h >> b/sound/soc/intel/skylake/skl-topology.h >> index 6db0fd7bad49..ffbd2e60fede 100644 >> --- a/sound/soc/intel/skylake/skl-topology.h >> +++ b/sound/soc/intel/skylake/skl-topology.h >> @@ -115,7 +115,10 @@ struct skl_cpr_gtw_cfg { >> u32 dma_buffer_size; >> u32 config_length; >> /* not mandatory; required only for DMIC/I2S */ >> - u32 config_data[1]; >> + union { >> + u32 x; >> + u32 config_data[0]; >> + }; > > Yeah, that could work, though the last member would be: > DECLARE_FLEX_ARRAY(u32, config_data); > otherwise the array is 0 length (rather than a proper flex array). > > But before that, let me see if I can track down where the size is being > used, in case we can avoid adding the padding. > I did spend some more time on this, apparently struct was missing one field according to IPC protocol. I've send fix for this.
diff --git a/sound/soc/intel/skylake/skl-topology.h b/sound/soc/intel/skylake/skl-topology.h index 6db0fd7bad49..ad94f8020c27 100644 --- a/sound/soc/intel/skylake/skl-topology.h +++ b/sound/soc/intel/skylake/skl-topology.h @@ -115,7 +115,7 @@ struct skl_cpr_gtw_cfg { u32 dma_buffer_size; u32 config_length; /* not mandatory; required only for DMIC/I2S */ - u32 config_data[1]; + u32 config_data[]; } __packed; struct skl_dma_control {
The kernel is globally removing the ambiguous 0-length and 1-element arrays in favor of flexible arrays, so that we can gain both compile-time and run-time array bounds checking[1]. In this instance, struct skl_cpr_cfg contains struct skl_cpr_gtw_cfg, which defined "config_data" as a 1-element array. Normally when switching from a 1-element array to a flex-array, any related size calculations must be adjusted too. However, it seems the original code was over-allocating space, since 1 extra u32 would be included by the sizeof(): param_size = sizeof(struct skl_cpr_cfg); param_size += mconfig->formats_config[SKL_PARAM_INIT].caps_size; But the copy uses caps_size bytes, and cap_size / 4 (i.e. sizeof(u32)) for the length tracking: memcpy(cpr_mconfig->gtw_cfg.config_data, mconfig->formats_config[SKL_PARAM_INIT].caps, mconfig->formats_config[SKL_PARAM_INIT].caps_size); cpr_mconfig->gtw_cfg.config_length = (mconfig->formats_config[SKL_PARAM_INIT].caps_size) / 4; Therefore, no size calculations need adjusting. Change the struct skl_cpr_gtw_cfg config_data member to be a true flexible array, which also fixes the over-allocation, and silences this memcpy run-time false positive: memcpy: detected field-spanning write (size 100) of single field "cpr_mconfig->gtw_cfg.config_data" at sound/soc/intel/skylake/skl-messages.c:554 (size 4) [1] For lots of details, see both: https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays https://people.kernel.org/kees/bounded-flexible-arrays-in-c Reported-by: Sasa Ostrouska <casaxa@gmail.com> Link: https://lore.kernel.org/all/CALFERdwvq5day_sbDfiUsMSZCQu9HG8-SBpOZDNPeMdZGog6XA@mail.gmail.com/ Cc: Cezary Rojewski <cezary.rojewski@intel.com> Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Cc: Liam Girdwood <liam.r.girdwood@linux.intel.com> Cc: Peter Ujfalusi <peter.ujfalusi@linux.intel.com> Cc: Bard Liao <yung-chuan.liao@linux.intel.com> Cc: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Cc: Kai Vehmanen <kai.vehmanen@linux.intel.com> Cc: Mark Brown <broonie@kernel.org> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Takashi Iwai <tiwai@suse.com> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> Cc: "Amadeusz Sławiński" <amadeuszx.slawinski@linux.intel.com> Cc: alsa-devel@alsa-project.org Signed-off-by: Kees Cook <keescook@chromium.org> --- sound/soc/intel/skylake/skl-topology.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)