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

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commit 6c89ffea60aa3b2a33ae7987de1e84bfb89e4c9e 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 Greg Kroah-Hartman
parent f8da2859e8
commit 4ba52d08b8
1 changed files with 8 additions and 8 deletions
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16
sound/soc/soc-pcm.c
View file

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