fix: off-by-one in DLT_MSG_READ_STRING allows dst[length] write past buffer end#843
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…buffer end Guard condition dstlength < length allows dstlength == length through, causing dst[length] = 0 to write one past end of buffer. Tighten to dstlength <= length to require space for the null terminator. CWE-193. Fixes COVESA#616.
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Closing this one. I opened a batch of PRs on this repo over a few days in early April without first doing the build-and-test verification a change in this codebase deserves, and they have been sitting in your queue since. Holding a review slot I didn't earn isn't fair to you, so I'm withdrawing them rather than leaving them open. The branch stays up. If any of the diff is useful, please take it freely — no attribution needed, and no need to reply here. Sorry for the noise. |
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Fixes #616.
Bug
`DLT_MSG_READ_STRING` in `include/dlt/dlt_common.h` writes a null terminator at `dst[length]` after copying `length` bytes into `dst`. The guard condition `dstlength < length` allows `dstlength == length` through to the else branch, where `dst[length]` is one past the end of the buffer (valid indices: `0..dstlength-1`).
Reproducer (ASAN-confirmed, from issue):
```
dlt-convert -a ./poc.dlt
```
CWE-193 (Off-by-one).
Fix
Tighten the guard from `dstlength < length` to `dstlength <= length`, requiring the destination buffer to hold at least `length + 1` bytes before proceeding.
```diff
```
Files: `include/dlt/dlt_common.h` — +1/−1
AI-assisted — authored with Claude, reviewed by Komada.