The clamping of idxYInv from H.266(V3) section 8.8.2.3 was missing.
This could lead to OOB reads from lmcs->pivot or input_pivot.
I also changed the derivation of the forward LMCS idx to use a shift
rather than a division for speed and as this is actually how the
variable is declared in the specification (8.7.5.2).
Signed-off-by: Frank Plowman <p...@frankplowman.com>
---
libavcodec/vvc/ps.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/libavcodec/vvc/ps.c b/libavcodec/vvc/ps.c
index 01b4615eda..fae6655cc0 100644
--- a/libavcodec/vvc/ps.c
+++ b/libavcodec/vvc/ps.c
@@ -786,7 +786,7 @@ static int lmcs_derive_lut(VVCLMCS *lmcs, const H266RawAPS
*rlmcs, const H266Raw
//derive lmcs_fwd_lut
for (uint16_t sample = 0; sample < max; sample++) {
- const int idx_y = sample / org_cw;
+ const int idx_y = sample >> shift;
const uint16_t fwd_sample = lmcs_derive_lut_sample(sample, lmcs->pivot,
input_pivot, scale_coeff, idx_y, max);
if (bit_depth > 8)
@@ -802,6 +802,7 @@ static int lmcs_derive_lut(VVCLMCS *lmcs, const H266RawAPS
*rlmcs, const H266Raw
uint16_t inv_sample;
while (i <= lmcs->max_bin_idx && sample >= lmcs->pivot[i + 1])
i++;
+ i = FFMIN(i, LMCS_MAX_BIN_SIZE - 1);
inv_sample = lmcs_derive_lut_sample(sample, input_pivot, lmcs->pivot,
inv_scale_coeff, i, max);
--
2.47.0
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