chenlin/Mujoco_WASM
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Avoid integer overflows when computing buffer sizes.

Browse Source 
If any field size would cause an overflow, fail to create the model.

PiperOrigin-RevId: 460466485
Change-Id: Ic8b84f3b56f2617c04ba04604729f0f76c6d62ee
This commit is contained in:
Nimrod Gileadi
2022-07-12 08:20:01 -07:00
committed by Copybara-Service
parent d5059f484d
commit af12322e9d
1 changed files with 37 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/engine/engine_io.c
+37 -6
View File
@@ -351,6 +351,31 @@ static void mj_setPtrModel(mjModel* m) {
} }
// increases buffer size without causing integer overflow, returns 0 if
// operation would cause overflow
// performs the following operations:
// *nbuffer += SKIP(*offset) + type_size*nr*nc;
// *offset += SKIP(*offset) + type_size*nr*nc;
static int safeAddToBufferSize(intptr_t* offset, int* nbuffer, size_t type_size, int nr, int nc) {
#if defined(__has_builtin) \
&& __has_builtin(__builtin_add_overflow) && __has_builtin(__builtin_mul_overflow)
// supported by GCC and Clang
int to_add = 0;
if (__builtin_mul_overflow(nc, nr, &to_add)) return 0;
if (__builtin_mul_overflow(to_add, type_size, &to_add)) return 0;
if (__builtin_add_overflow(to_add, SKIP(*offset), &to_add)) return 0;
if (__builtin_add_overflow(*nbuffer, to_add, nbuffer)) return 0;
if (__builtin_add_overflow(*offset, to_add, offset)) return 0;
#else
// TODO: offer a safe implementation for MSVC or other compilers that don't have the builtins
*nbuffer += SKIP(*offset) + type_size*nr*nc;
*offset += SKIP(*offset) + type_size*nr*nc;
#endif
return 1;
}
// allocate and initialize mjModel structure // allocate and initialize mjModel structure
mjModel* mj_makeModel(int nq, int nv, int nu, int na, int nbody, int njnt, mjModel* mj_makeModel(int nq, int nv, int nu, int na, int nbody, int njnt,
@@ -435,9 +460,12 @@ mjModel* mj_makeModel(int nq, int nv, int nu, int na, int nbody, int njnt,
// compute buffer size // compute buffer size
m->nbuffer = 0; m->nbuffer = 0;
#define X(type, name, nr, nc) \ #define X(type, name, nr, nc) \
m->nbuffer += SKIP(offset) + sizeof(type)*(m->nr)*(nc); \ if (!safeAddToBufferSize(&offset, &m->nbuffer, sizeof(type), m->nr, nc)) { \
offset += SKIP(offset) + sizeof(type)*(m->nr)*(nc); mju_warning("Invalid model: " #name " too large."); \
mj_deleteModel(m); \
return 0; \
}
MJMODEL_POINTERS MJMODEL_POINTERS
#undef X #undef X
@@ -799,9 +827,12 @@ static mjData* _makeData(const mjModel* m) {
// compute buffer size // compute buffer size
d->nbuffer = 0; d->nbuffer = 0;
#define X(type, name, nr, nc) \ #define X(type, name, nr, nc) \
d->nbuffer += SKIP(offset) + sizeof(type)*(m->nr)*(nc); \ if (!safeAddToBufferSize(&offset, &d->nbuffer, sizeof(type), m->nr, nc)) { \
offset += SKIP(offset) + sizeof(type)*(m->nr)*(nc); mju_warning("Invalid data: " #name " too large."); \
mj_deleteData(d); \
return 0; \
}
MJDATA_POINTERS MJDATA_POINTERS
#undef X #undef X