Package: release.debian.org Severity: normal Tags: bullseye User: release.debian....@packages.debian.org Usertags: pu
Hello, I'd like to have version 0.10.2-2+deb11u2 of speech-dispatcher uploaded to bullseye. [ Reason ] As reported on https://github.com/espeak-ng/espeak-ng/issues/1554 there is a longstanding buffer overflow issue in espeak-ng. It appears to users as artifacts in the speech that makes it sometimes less inteligible. But since they are due to a buffer overflow, the consequences could actually be way worse, notably since in the context of a screen reader using espeak-ng as speech synthesis, the data produced in the buffer comes from e.g. whatever webpage that the user is browsing, thus potential for security issues. This is not a regression from oldstable, since the bug has basically always been there. [ Impact ] If it is no included, users will still hear artifacts, and would also potentially be exposed to security issues due to the buffer overflows. [ Tests ] We made manual tests that confirmed that the change fixes the issue. We also confirmed the buffer overflow in espeak-ng's valgrind/asan CI. [ Risks ] The change is very trivial. It makes the speech synthesis processing a bit more expensive, but that will be very lightweight. [ Checklist ] [X] *all* changes are documented in the d/changelog [X] I reviewed all changes and I approve them [X] attach debdiff against the package in (old)stable [X] the issue is verified as fixed in unstable [ Changes ] The patch simply lowers the audio buffer size from 3s to 300ms. 3s was originally chosen so that large chunks of audio are processed at a time, but this is what is making espeak-ng overflow its synthesis buffers. The exact overflows should ideally be fixed in espeak-ng of course, but apparently this will be very involved, and it is way simpler to just make speech-dispatcher not request so large buffers. espeak-ng itself defaults to 60ms, and on Windows NVDA uses 300ms and does not suffer from buffer overflows. In practice, the overflows that we observed in https://github.com/espeak-ng/espeak-ng/issues/1554 happens with buffer around 900ms. 300ms seems a fairly safe value while being not too small so as to process not-so-small chunks of audio at a time. Samuel
diff --git a/debian/changelog b/debian/changelog index 6fea892..b6120a2 100644 --- a/debian/changelog +++ b/debian/changelog @@ -1,3 +1,9 @@ +speech-dispatcher (0.10.2-2+deb11u2) bullseye; urgency=medium + + * patches/buffer_size: Reduce espeak buffer size to avoid synth artifacts. + + -- Samuel Thibault <sthiba...@debian.org> Wed, 30 Nov 2022 21:10:17 +0100 + speech-dispatcher (0.10.2-2+deb11u1) bullseye; urgency=medium * patches/generic-set-voice-name: Fix setting voice name for the generic diff --git a/debian/patches/buffer_size b/debian/patches/buffer_size new file mode 100644 index 0000000..2b13443 --- /dev/null +++ b/debian/patches/buffer_size @@ -0,0 +1,35 @@ +commit be4c3585ead45716b8f49300b50c30fdb6eee266 +Author: Alexander Epaneshnikov <aarnaa...@gmail.com> +Date: Thu Nov 24 01:41:40 2022 +0300 + + espeak: set buffer size to 300 + + this fixes #793 + ref for buffer size: https://github.com/nvaccess/nvda/blob/a6fb2392083b5fa1bae926102135ad452746ad3c/source/synthDrivers/_espeak.py#L338 + +diff --git a/config/modules/espeak-ng.conf b/config/modules/espeak-ng.conf +index d02704e9..9677bc99 100644 +--- a/config/modules/espeak-ng.conf ++++ b/config/modules/espeak-ng.conf +@@ -41,7 +41,7 @@ EspeakMaxRate 449 + # -- Internal parameters -- + + # Number of ms of audio returned by the espeak callback function. +-EspeakAudioChunkSize 3000 ++EspeakAudioChunkSize 300 + + # Maximum number of samples to buffer in playback queue. + EspeakAudioQueueMaxSize 441000 +diff --git a/config/modules/espeak.conf b/config/modules/espeak.conf +index 3abc422b..cbd453b7 100644 +--- a/config/modules/espeak.conf ++++ b/config/modules/espeak.conf +@@ -41,7 +41,7 @@ EspeakMaxRate 449 + # -- Internal parameters -- + + # Number of ms of audio returned by the espeak callback function. +-EspeakAudioChunkSize 3000 ++EspeakAudioChunkSize 300 + + # Maximum number of samples to buffer in playback queue. + EspeakAudioQueueMaxSize 441000 diff --git a/debian/patches/series b/debian/patches/series index 1f09fb7..5619c8a 100644 --- a/debian/patches/series +++ b/debian/patches/series @@ -2,3 +2,4 @@ doc-figures systemd-debian mbrola-paths generic-set-voice-name +buffer_size
