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authorTakashi Iwai <tiwai@suse.de>2020-12-18 15:56:25 +0100
committerTakashi Iwai <tiwai@suse.de>2020-12-18 17:09:28 +0100
commit618de0f4ef11acd8cf26902e65493d46cc20cc89 (patch)
treea56c4b1232cfe02a3dcdc09373c5c85061e176c4
parent5c1733e33c888a3cb7f576564d8ad543d5ad4a9e (diff)
downloadlinux-618de0f4ef11acd8cf26902e65493d46cc20cc89.tar.bz2
ALSA: pcm: Clear the full allocated memory at hw_params
The PCM hw_params core function tries to clear up the PCM buffer before actually using for avoiding the information leak from the previous usages or the usage before a new allocation. It performs the memset() with runtime->dma_bytes, but this might still leave some remaining bytes untouched; namely, the PCM buffer size is aligned in page size for mmap, hence runtime->dma_bytes doesn't necessarily cover all PCM buffer pages, and the remaining bytes are exposed via mmap. This patch changes the memory clearance to cover the all buffer pages if the stream is supposed to be mmap-ready (that guarantees that the buffer size is aligned in page size). Reviewed-by: Lars-Peter Clausen <lars@metafoo.de> Link: https://lore.kernel.org/r/20201218145625.2045-3-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--sound/core/pcm_native.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 47b155a49226..9f3f8e953ff0 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -755,8 +755,13 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
runtime->boundary *= 2;
/* clear the buffer for avoiding possible kernel info leaks */
- if (runtime->dma_area && !substream->ops->copy_user)
- memset(runtime->dma_area, 0, runtime->dma_bytes);
+ if (runtime->dma_area && !substream->ops->copy_user) {
+ size_t size = runtime->dma_bytes;
+
+ if (runtime->info & SNDRV_PCM_INFO_MMAP)
+ size = PAGE_ALIGN(size);
+ memset(runtime->dma_area, 0, size);
+ }
snd_pcm_timer_resolution_change(substream);
snd_pcm_set_state(substream, SNDRV_PCM_STATE_SETUP);