| Message ID | 20240512000349.3381912-1-michael@niedermayer.cc |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel,1/5] avcodec/lpc: copy levenson coeffs only when they have been computed | expand |
On 12/05/2024 02:03, Michael Niedermayer wrote: > Fixes: CID1473514 Uninitialized scalar variable > > Sponsored-by: Sovereign Tech Fund > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > --- > 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<max_order; j++) > - m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; > + if (lpc_passes > 1) > + for(j=0; j<max_order; j++) > + m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; > > for(; pass<lpc_passes; 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.
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 <michael@niedermayer.cc> > > --- > > 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<max_order; j++) > > - m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; > > + if (lpc_passes > 1) > > + for(j=0; j<max_order; j++) > > + m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; > > for(; pass<lpc_passes; 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 [...]
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 <michael@niedermayer.cc> >>> --- >>> 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<max_order; j++) >>> - m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; >>> + if (lpc_passes > 1) >>> + for(j=0; j<max_order; j++) >>> + m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; >>> for(; pass<lpc_passes; 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.
On Sun, May 12, 2024 at 02:29:57AM +0200, Lynne via ffmpeg-devel wrote: > 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 <michael@niedermayer.cc> > > > > --- > > > > 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<max_order; j++) > > > > - m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; > > > > + if (lpc_passes > 1) > > > > + for(j=0; j<max_order; j++) > > > > + m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; > > > > for(; pass<lpc_passes; 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. ok, will apply with such note thx [...]
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<max_order; j++) - m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; + if (lpc_passes > 1) + for(j=0; j<max_order; j++) + m[0].coeff[max_order-1][j] = -lpc[max_order-1][j]; for(; pass<lpc_passes; pass++){ avpriv_init_lls(&m[pass&1], max_order);
Fixes: CID1473514 Uninitialized scalar variable Sponsored-by: Sovereign Tech Fund Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> --- libavcodec/lpc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)