ASoC: pcm: Fix possible buffer overflow in dpcm state sysfs output

commit 6c89ffea60 upstream.

dpcm_show_state() invokes multiple snprintf() calls to concatenate
formatted strings on the fixed size buffer.  The usage of snprintf()
is supposed for avoiding the buffer overflow, but it doesn't work as
expected because snprintf() doesn't return the actual output size but
the size to be written.

Fix this bug by replacing all snprintf() calls with scnprintf()
calls.

Fixes: f86dcef87b ("ASoC: dpcm: Add debugFS support for DPCM")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20200218111737.14193-4-tiwai@suse.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Iwai
2020-02-18 12:17:37 +01:00
committed by Chris
parent 44e065b0d3
commit 056b5e967c

View File

@@ -2979,16 +2979,16 @@ static ssize_t dpcm_show_state(struct snd_soc_pcm_runtime *fe,
ssize_t offset = 0;
/* FE state */
offset += snprintf(buf + offset, size - offset,
offset += scnprintf(buf + offset, size - offset,
"[%s - %s]\n", fe->dai_link->name,
stream ? "Capture" : "Playback");
offset += snprintf(buf + offset, size - offset, "State: %s\n",
offset += scnprintf(buf + offset, size - offset, "State: %s\n",
dpcm_state_string(fe->dpcm[stream].state));
if ((fe->dpcm[stream].state >= SND_SOC_DPCM_STATE_HW_PARAMS) &&
(fe->dpcm[stream].state <= SND_SOC_DPCM_STATE_STOP))
offset += snprintf(buf + offset, size - offset,
offset += scnprintf(buf + offset, size - offset,
"Hardware Params: "
"Format = %s, Channels = %d, Rate = %d\n",
snd_pcm_format_name(params_format(params)),
@@ -2996,10 +2996,10 @@ static ssize_t dpcm_show_state(struct snd_soc_pcm_runtime *fe,
params_rate(params));
/* BEs state */
offset += snprintf(buf + offset, size - offset, "Backends:\n");
offset += scnprintf(buf + offset, size - offset, "Backends:\n");
if (list_empty(&fe->dpcm[stream].be_clients)) {
offset += snprintf(buf + offset, size - offset,
offset += scnprintf(buf + offset, size - offset,
" No active DSP links\n");
goto out;
}
@@ -3008,16 +3008,16 @@ static ssize_t dpcm_show_state(struct snd_soc_pcm_runtime *fe,
struct snd_soc_pcm_runtime *be = dpcm->be;
params = &dpcm->hw_params;
offset += snprintf(buf + offset, size - offset,
offset += scnprintf(buf + offset, size - offset,
"- %s\n", be->dai_link->name);
offset += snprintf(buf + offset, size - offset,
offset += scnprintf(buf + offset, size - offset,
" State: %s\n",
dpcm_state_string(be->dpcm[stream].state));
if ((be->dpcm[stream].state >= SND_SOC_DPCM_STATE_HW_PARAMS) &&
(be->dpcm[stream].state <= SND_SOC_DPCM_STATE_STOP))
offset += snprintf(buf + offset, size - offset,
offset += scnprintf(buf + offset, size - offset,
" Hardware Params: "
"Format = %s, Channels = %d, Rate = %d\n",
snd_pcm_format_name(params_format(params)),