Swatantra-66 opened a new pull request, #21528:
URL: https://github.com/apache/nuttx/pull/21528
## Summary
POSIX IEEE Std 1003.1 explicitly mandates for `recvmsg()`:
> *"The `recvmsg()` function shall fail with `[EINVAL]` if the sum of the
`iov_len` values in the `msg_iov` array overflows an `ssize_t`."*
While `inet_sendmsg()` in `net/inet/inet_sockif.c` already implements this
boundary check, `inet_recvmsg()` and `psock_tcp_recvfrom()` omitted it.
In `psock_tcp_recvfrom()`, received bytes were accumulated into `ssize_t
nrecv`. If the total capacity of the user's `iovec` array exceeded `SSIZE_MAX`,
`nrecv` suffered signed integer overflow (undefined behavior in C) and wrapped
negative. Callers interpreted this negative return value as a negated error
code (e.g. `-EINVAL` or `-ECONNRESET`) despite data having been successfully
received into user buffers.
This change validates that the accumulated length of the `iovec` array fits
in `ssize_t` before processing, failing upfront with `-EINVAL`.
### Behavior Comparison
| Subsystem / Path | Before This PR | With This PR | POSIX Requirement |
| :--- | :--- | :--- | :--- |
| **`inet_sendmsg`** | Validates `iov_len > SSIZE_MAX - len` (`-EINVAL`) |
Validates `iov_len > SSIZE_MAX - len` (`-EINVAL`) | IEEE Std 1003.1 `sendmsg` |
| **`inet_recvmsg`** | No overflow check (missing) | Validates `iov_len >
SSIZE_MAX - len` (`-EINVAL`) | IEEE Std 1003.1 `recvmsg` |
| **`psock_tcp_recvfrom`** | Unchecked `nrecv += ret` wraps negative |
Validates upfront before lock (`-EINVAL`) | Prevents signed overflow / UB |
## Impact
- Conforms `recvmsg()` to POSIX IEEE Std 1003.1 for `AF_INET` and `AF_INET6`
sockets.
- Prevents signed integer overflow and return value corruption on large
scatter/gather receive requests.
- No ABI change. Flat, protected, and kernel builds unaffected.
## Testing
Host: Linux x86_64 / Alpine Docker.
- **Checkpatch**: `tools/checkpatch.sh -r -K -m -g HEAD~1..HEAD` passes:
```text
✔️ All checks pass.
```
- **Coding Style (`nxstyle`)**:
- `net/inet/inet_sockif.c`: 0 errors, 0 warnings
- `net/tcp/tcp_recvfrom.c`: 0 errors, 0 warnings
- **Spell check**: `codespell` reports 0 issues.
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