From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id C69854AAA0 for ; Sun, 12 May 2024 00:30:08 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 2F5E368D591; Sun, 12 May 2024 03:30:06 +0300 (EEST) Received: from vidala.lynne.ee (vidala.pars.ee [116.203.72.101]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 52AF968D43F for ; Sun, 12 May 2024 03:29:59 +0300 (EEST) Message-ID: Date: Sun, 12 May 2024 02:29:57 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: ffmpeg-devel@ffmpeg.org References: <20240512000349.3381912-1-michael@niedermayer.cc> <83bec738-e2dc-41a3-88af-a53ab6958628@lynne.ee> <20240512001850.GV6420@pb2> Content-Language: en-US In-Reply-To: <20240512001850.GV6420@pb2> Subject: Re: [FFmpeg-devel] [PATCH 1/5] avcodec/lpc: copy levenson coeffs only when they have been computed X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Lynne via ffmpeg-devel Reply-To: FFmpeg development discussions and patches Cc: Lynne Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: On 12/05/2024 02:18, Michael Niedermayer wrote: > On Sun, May 12, 2024 at 02:13:06AM +0200, Lynne via ffmpeg-devel wrote: >> On 12/05/2024 02:03, Michael Niedermayer wrote: >>> Fixes: CID1473514 Uninitialized scalar variable >>> >>> Sponsored-by: Sovereign Tech Fund >>> Signed-off-by: Michael Niedermayer >>> --- >>> libavcodec/lpc.c | 5 +++-- >>> 1 file changed, 3 insertions(+), 2 deletions(-) >>> >>> diff --git a/libavcodec/lpc.c b/libavcodec/lpc.c >>> index 8305cc0596a..981dacce8a5 100644 >>> --- a/libavcodec/lpc.c >>> +++ b/libavcodec/lpc.c >>> @@ -282,8 +282,9 @@ int ff_lpc_calc_coefs(LPCContext *s, >>> double av_uninit(weight); >>> memset(var, 0, FFALIGN(MAX_LPC_ORDER+1,4)*sizeof(*var)); >>> - for(j=0; j>> - m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; >>> + if (lpc_passes > 1) >>> + for(j=0; j>> + m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; >>> for(; pass>> avpriv_init_lls(&m[pass&1], max_order); >> >> max_order is a function argument, I don't think that's the right place to >> fix this. > > max_orders is fine > > what the problem is, is that CHOLESKY with lpc_passes = 1 > skips the first pass LEVINSON but this line copies the output > from LEVINSON so it copies Uninitialized data. > a few lines later thats cleared with avpriv_init_lls() > but that access to uninitialized data i think is undefined behavior > > if my analysis is not wrong then i think my fix is correct > > thx > > [...] > > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". Ah, I see. Could you put a small comment above, like: /* Avoids initializing with an unused value when max_order == 1 */? Other than that looks fine. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".