PointerWrap and the Do() overloads around it are how every savestate is
written and read, and had no direct coverage. Everything read back came off
disk, so the corrupt-input paths matter as much as the round trips.
Three bugs, all in the bounds checking added in 58d4759ceb:
1. sizeof(T) is not a lower bound on how many bytes an element serializes to.
It only holds for the types DoHelper_ writes out raw. A std::string is 32-40
bytes in memory and serializes to as few as five; a T* serializes to whatever
T::DoState() writes. So DoVector/DoList/DoSet/DoMap could reject a perfectly
valid savestate whenever count * sizeof(element) exceeded the bytes left in
the buffer. That is not hypothetical: pspFileSystem is serialized dead last
in SaveStart::DoState, and MetaFileSystem::DoState does Do(p, currentDir) on
a std::map<int, std::string>, so the check runs with only a few hundred bytes
remaining and claims 44 bytes per entry against roughly 22 actual. Added
SerializeMinElemSize<T>(), mirroring DoHelper_'s own condition, and used it
in all five containers. The bound is only loosened, so nothing that loaded
before can stop loading.
2. Do(p, std::map<K, T *> &) deletes every value before reading the new ones,
and DoMap then returned on a bad count without clearing - leaving the map
full of freed pointers to be used or deleted again. Six live maps go through
this (sceMpeg, sceMp3, sceAac, sceFont, sceHeap, sceKernelThread's pending
calls), so a corrupt savestate meant a use-after-free. Clear before the guard
can bail out, in DoMap, DoMultimap and DoSet.
3. The wstring and u16string overloads validated stringLen < 0 but not 0, and
didn't require a whole number of characters. read() computes
stringLen / sizeof(char) - 1, so a length of 0 resized to SIZE_MAX and
memcpy'd with a wrapped-around size. PSPOskDialog::DoState serializes both
(inputChars at v2, a legacy wstring below that), so this was reachable: the
test aborts the process without the fix.
The test covers round trips of PODs, strings (empty, embedded NUL), vector,
map, set, list and map-of-pointers, section titles and version gating in both
directions, marker mismatches, measure-vs-write checkpoint disagreement, the
error latch dropping to MODE_NOOP, every truncation of a valid buffer, and
hand-corrupted counts and lengths.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GZq8ZtJmFY7bkX5FVkr3P9
PointerWrap tracked no end-of-buffer, so DoState() implementations could
read past the end of a crafted or truncated savestate via DoVoid's
unchecked memcpy, and DoVector could resize to an attacker-controlled
size before reading.
- PointerWrap now tracks a read end; DoVoid/ExpectVoid fail (MODE_NOOP)
before reading out of bounds.
- String reads are bounds-checked for the whole string including NUL.
- DoVector rejects sizes that can't fit in the remaining buffer.
- LoadPtr takes the buffer size and sets the read end.
- Capping the decompression buffer allocation in LoadFile.
