py/stream: Check for stream read function returning too many bytes. #13572
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Code size report: |
Codecov ReportAttention: Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## master #13572 +/- ##
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- Coverage 98.39% 98.38% -0.01%
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Files 161 161
Lines 21078 21085 +7
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+ Hits 20739 20744 +5
- Misses 339 341 +2 ☔ View full report in Codecov by Sentry. |
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A positive result here can result in eventual memory corruption as littlefs expects the result of a cache read/write function to be 0 or a negative integer for an error. Closes micropython#13046 This work was funded through GitHub Sponsors. Signed-off-by: Angus Gratton <angus@redyak.com.au>
This only happens if the underlying stream implementation is malformed, but results in unsigned integer overflow and out of bounds read otherwise. Second fix for micropython#13046 - allows for possibility an invalid result comes back from a different stream implementation. This work was funded through GitHub Sponsors. Signed-off-by: Angus Gratton <angus@redyak.com.au>
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Closes #13046. This is two fixes:
mp_vfs_blockdev_read_ext/mp_vfs_blockdev_write_extto be 0 or a negative integer. Returning positive integers here confuses littlefs (see lfs1.c:66 for example) and led to the linked bug. In general it seems like it can lead to unexpected behaviour, in libraries not part of MicroPython.Either one of these is sufficient to fix the linked issue, but checking both seem potentially worthwhile as it's possible for other similar cases to arise (either different stream implementations that return the wrong length, or other errors in block device consumers that are returned invalid results.)
This work was funded through GitHub Sponsors.