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hw/audio/sb16: Restrict I/O sampling rate range for command 41h/42h 

The I/O sampling rate range is enforced to 5000 to 45000HZ according to
commit a2cd86a9. Setting I/O sampling rate with command 41h/42h, a guest
user can break this assumption and trigger an assertion in audio_calloc
via command 0xd4. This patch restricts the I/O sampling rate range for
command 41h/42h.

Fixes: 85571bc741 ("audio merge (malc)")
Signed-off-by: Qiang Liu <cyruscyliu@gmail.com>
Message-Id: <1624502687-5214-1-git-send-email-cyruscyliu@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Qiang Liu 2021-06-24 10:44:47 +08:00 committed by Gerd Hoffmann
parent eb1a35e47a
commit 60e543f5ce
2 changed files with 36 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
hw/audio/sb16.c
View File

@ -229,6 +229,23 @@ static void continue_dma8 (SB16State *s)
control (s, 1); control (s, 1);
} }
static inline int restrict_sampling_rate(int freq)
{
if (freq < SAMPLE_RATE_MIN) {
qemu_log_mask(LOG_GUEST_ERROR,
"sampling range too low: %d, increasing to %u\n",
freq, SAMPLE_RATE_MIN);
return SAMPLE_RATE_MIN;
} else if (freq > SAMPLE_RATE_MAX) {
qemu_log_mask(LOG_GUEST_ERROR,
"sampling range too high: %d, decreasing to %u\n",
freq, SAMPLE_RATE_MAX);
return SAMPLE_RATE_MAX;
} else {
return freq;
}
}
static void dma_cmd8 (SB16State *s, int mask, int dma_len) static void dma_cmd8 (SB16State *s, int mask, int dma_len)
{ {
s->fmt = AUDIO_FORMAT_U8; s->fmt = AUDIO_FORMAT_U8;
@ -244,17 +261,7 @@ static void dma_cmd8 (SB16State *s, int mask, int dma_len)
int tmp = (256 - s->time_const); int tmp = (256 - s->time_const);
s->freq = (1000000 + (tmp / 2)) / tmp; s->freq = (1000000 + (tmp / 2)) / tmp;
} }
if (s->freq < SAMPLE_RATE_MIN) { s->freq = restrict_sampling_rate(s->freq);
qemu_log_mask(LOG_GUEST_ERROR,
"sampling range too low: %d, increasing to %u\n",
s->freq, SAMPLE_RATE_MIN);
s->freq = SAMPLE_RATE_MIN;
} else if (s->freq > SAMPLE_RATE_MAX) {
qemu_log_mask(LOG_GUEST_ERROR,
"sampling range too high: %d, decreasing to %u\n",
s->freq, SAMPLE_RATE_MAX);
s->freq = SAMPLE_RATE_MAX;
}
if (dma_len != -1) { if (dma_len != -1) {
s->block_size = dma_len << s->fmt_stereo; s->block_size = dma_len << s->fmt_stereo;
@ -768,7 +775,7 @@ static void complete (SB16State *s)
* and FT2 sets output freq with this (go figure). Compare: * and FT2 sets output freq with this (go figure). Compare:
* http://homepages.cae.wisc.edu/~brodskye/sb16doc/sb16doc.html#SamplingRate * http://homepages.cae.wisc.edu/~brodskye/sb16doc/sb16doc.html#SamplingRate
*/ */
s->freq = dsp_get_hilo (s); s->freq = restrict_sampling_rate(dsp_get_hilo(s));
ldebug ("set freq %d\n", s->freq); ldebug ("set freq %d\n", s->freq);
break; break;

17
tests/qtest/fuzz-sb16-test.c
View File

@ -37,6 +37,22 @@ static void test_fuzz_sb16_0x91(void)
qtest_quit(s); qtest_quit(s);
} }
/*
* This used to trigger the assert in audio_calloc
* through command 0xd4
*/
static void test_fuzz_sb16_0xd4(void)
{
QTestState *s = qtest_init("-M pc -display none "
"-device sb16,audiodev=none "
"-audiodev id=none,driver=none");
qtest_outb(s, 0x22c, 0x41);
qtest_outb(s, 0x22c, 0x00);
qtest_outb(s, 0x22c, 0x14);
qtest_outb(s, 0x22c, 0xd4);
qtest_quit(s);
}
int main(int argc, char **argv) int main(int argc, char **argv)
{ {
const char *arch = qtest_get_arch(); const char *arch = qtest_get_arch();
@ -46,6 +62,7 @@ int main(int argc, char **argv)
if (strcmp(arch, "i386") == 0) { if (strcmp(arch, "i386") == 0) {
qtest_add_func("fuzz/test_fuzz_sb16/1c", test_fuzz_sb16_0x1c); qtest_add_func("fuzz/test_fuzz_sb16/1c", test_fuzz_sb16_0x1c);
qtest_add_func("fuzz/test_fuzz_sb16/91", test_fuzz_sb16_0x91); qtest_add_func("fuzz/test_fuzz_sb16/91", test_fuzz_sb16_0x91);
qtest_add_func("fuzz/test_fuzz_sb16/d4", test_fuzz_sb16_0xd4);
} }
return g_test_run(); return g_test_run();