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 <mich...@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
[...]
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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.
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