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Fix (unreported) bad memory access in read/write code of MeshDeform modifier.

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This abuse of one one size value to handle another allocated array of a
different size is bad in itself, but at least now read/write code of
this modifier should not risk invalid memory access anymore.

NOTE: invalid memory access would in practice only happen in case endian
switch would be performed at read time I think (those switches only check
for given length being non-zero, not for a NULL data pointer...).
This commit is contained in:
Bastien Montagne
2022-05-12 17:19:22 +02:00
parent d9effc1cc6
commit 32fd85e6f9
1 changed files with 17 additions and 2 deletions
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19
source/blender/modifiers/intern/MOD_meshdeform.c
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@@ -587,7 +587,16 @@ static void blendWrite(BlendWriter *writer, const ModifierData *md)
int size = mmd->dyngridsize;
BLO_write_struct_array(writer, MDefInfluence, mmd->influences_num, mmd->bindinfluences);
BLO_write_int32_array(writer, mmd->verts_num + 1, mmd->bindoffsets);
/* NOTE: `bindoffset` is abusing `verts_num + 1` as its size, this becomes an incorrect value in
* case `verts_num == 0`, since `bindoffset` is then NULL, not a size 1 allocated array. */
if (mmd->verts_num > 0) {
BLO_write_int32_array(writer, mmd->verts_num + 1, mmd->bindoffsets);
}
else {
BLI_assert(mmd->bindoffsets == NULL);
}
BLO_write_float3_array(writer, mmd->cage_verts_num, mmd->bindcagecos);
BLO_write_struct_array(writer, MDefCell, size * size * size, mmd->dyngrid);
BLO_write_struct_array(writer, MDefInfluence, mmd->influences_num, mmd->dyninfluences);
@@ -599,7 +608,13 @@ static void blendRead(BlendDataReader *reader, ModifierData *md)
MeshDeformModifierData *mmd = (MeshDeformModifierData *)md;
BLO_read_data_address(reader, &mmd->bindinfluences);
BLO_read_int32_array(reader, mmd->verts_num + 1, &mmd->bindoffsets);
/* NOTE: `bindoffset` is abusing `verts_num + 1` as its size, this becomes an incorrect value in
* case `verts_num == 0`, since `bindoffset` is then NULL, not a size 1 allocated array. */
if (mmd->verts_num > 0) {
BLO_read_int32_array(reader, mmd->verts_num + 1, &mmd->bindoffsets);
}
BLO_read_float3_array(reader, mmd->cage_verts_num, &mmd->bindcagecos);
BLO_read_data_address(reader, &mmd->dyngrid);
BLO_read_data_address(reader, &mmd->dyninfluences);