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ASoC: Intel: Boards: Fix NULL pointer deref in BYT/CHT boards harder

Since commit 13f58267cda3 ("ASoC: soc.h: don't create dummy Component
via COMP_DUMMY()") dummy codecs declared like this:

SND_SOC_DAILINK_DEF(dummy,
DAILINK_COMP_ARRAY(COMP_DUMMY()));

expand to:

static struct snd_soc_dai_link_component dummy[] = {
};

Which means that dummy is a zero sized array and thus dais[i].codecs should
not be dereferenced *at all* since it points to the address of the next
variable stored in the data section as the "dummy" variable has an address
but no size, so even dereferencing dais[0] is already an out of bounds
array reference.

Which means that the if (dais[i].codecs->name) check added in
commit 7d99a70b6595 ("ASoC: Intel: Boards: Fix NULL pointer deref
in BYT/CHT boards") relies on that the part of the next variable which
the name member maps to just happens to be NULL.

Which apparently so far it usually is, except when it isn't
and then it results in crashes like this one:

[ 28.795659] BUG: unable to handle page fault for address: 0000000000030011
...
[ 28.795780] Call Trace:
[ 28.795787] <TASK>
...
[ 28.795862] ? strcmp+0x18/0x40
[ 28.795872] 0xffffffffc150c605
[ 28.795887] platform_probe+0x40/0xa0
...
[ 28.795979] ? __pfx_init_module+0x10/0x10 [snd_soc_sst_bytcr_wm5102]

Really fix things this time around by checking dais.num_codecs != 0.

Fixes: 7d99a70b6595 ("ASoC: Intel: Boards: Fix NULL pointer deref in BYT/CHT boards")
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://patch.msgid.link/20240823074217.14653-1-hdegoede@redhat.com
Signed-off-by: Mark Brown <broonie@kernel.org>

authored by

Hans de Goede and committed by
Mark Brown 0cc65482 bb448556

+9 -9
+1 -1
sound/soc/intel/boards/bxt_rt298.c
··· 605 605 int i; 606 606 607 607 for (i = 0; i < ARRAY_SIZE(broxton_rt298_dais); i++) { 608 - if (card->dai_link[i].codecs->name && 608 + if (card->dai_link[i].num_codecs && 609 609 !strncmp(card->dai_link[i].codecs->name, "i2c-INT343A:00", 610 610 I2C_NAME_SIZE)) { 611 611 if (!strncmp(card->name, "broxton-rt298",
+1 -1
sound/soc/intel/boards/bytcht_cx2072x.c
··· 241 241 242 242 /* fix index of codec dai */ 243 243 for (i = 0; i < ARRAY_SIZE(byt_cht_cx2072x_dais); i++) { 244 - if (byt_cht_cx2072x_dais[i].codecs->name && 244 + if (byt_cht_cx2072x_dais[i].num_codecs && 245 245 !strcmp(byt_cht_cx2072x_dais[i].codecs->name, 246 246 "i2c-14F10720:00")) { 247 247 dai_index = i;
+1 -1
sound/soc/intel/boards/bytcht_da7213.c
··· 245 245 246 246 /* fix index of codec dai */ 247 247 for (i = 0; i < ARRAY_SIZE(dailink); i++) { 248 - if (dailink[i].codecs->name && 248 + if (dailink[i].num_codecs && 249 249 !strcmp(dailink[i].codecs->name, "i2c-DLGS7213:00")) { 250 250 dai_index = i; 251 251 break;
+1 -1
sound/soc/intel/boards/bytcht_es8316.c
··· 546 546 547 547 /* fix index of codec dai */ 548 548 for (i = 0; i < ARRAY_SIZE(byt_cht_es8316_dais); i++) { 549 - if (byt_cht_es8316_dais[i].codecs->name && 549 + if (byt_cht_es8316_dais[i].num_codecs && 550 550 !strcmp(byt_cht_es8316_dais[i].codecs->name, 551 551 "i2c-ESSX8316:00")) { 552 552 dai_index = i;
+1 -1
sound/soc/intel/boards/bytcr_rt5640.c
··· 1677 1677 1678 1678 /* fix index of codec dai */ 1679 1679 for (i = 0; i < ARRAY_SIZE(byt_rt5640_dais); i++) { 1680 - if (byt_rt5640_dais[i].codecs->name && 1680 + if (byt_rt5640_dais[i].num_codecs && 1681 1681 !strcmp(byt_rt5640_dais[i].codecs->name, 1682 1682 "i2c-10EC5640:00")) { 1683 1683 dai_index = i;
+1 -1
sound/soc/intel/boards/bytcr_rt5651.c
··· 910 910 911 911 /* fix index of codec dai */ 912 912 for (i = 0; i < ARRAY_SIZE(byt_rt5651_dais); i++) { 913 - if (byt_rt5651_dais[i].codecs->name && 913 + if (byt_rt5651_dais[i].num_codecs && 914 914 !strcmp(byt_rt5651_dais[i].codecs->name, 915 915 "i2c-10EC5651:00")) { 916 916 dai_index = i;
+1 -1
sound/soc/intel/boards/bytcr_wm5102.c
··· 605 605 606 606 /* find index of codec dai */ 607 607 for (i = 0; i < ARRAY_SIZE(byt_wm5102_dais); i++) { 608 - if (byt_wm5102_dais[i].codecs->name && 608 + if (byt_wm5102_dais[i].num_codecs && 609 609 !strcmp(byt_wm5102_dais[i].codecs->name, 610 610 "wm5102-codec")) { 611 611 dai_index = i;
+1 -1
sound/soc/intel/boards/cht_bsw_rt5645.c
··· 569 569 570 570 /* set correct codec name */ 571 571 for (i = 0; i < ARRAY_SIZE(cht_dailink); i++) 572 - if (cht_dailink[i].codecs->name && 572 + if (cht_dailink[i].num_codecs && 573 573 !strcmp(cht_dailink[i].codecs->name, 574 574 "i2c-10EC5645:00")) { 575 575 dai_index = i;
+1 -1
sound/soc/intel/boards/cht_bsw_rt5672.c
··· 466 466 467 467 /* find index of codec dai */ 468 468 for (i = 0; i < ARRAY_SIZE(cht_dailink); i++) { 469 - if (cht_dailink[i].codecs->name && 469 + if (cht_dailink[i].num_codecs && 470 470 !strcmp(cht_dailink[i].codecs->name, RT5672_I2C_DEFAULT)) { 471 471 dai_index = i; 472 472 break;