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Bug #525
openPotential clash when custom get_flash_region() called in erase_write
Start date:
02/05/2024
Due date:
% Done:
0%
Estimated time:
Affected versions:
Needs backport to:
Affected hardware:
Affected OS:
Description
erase_write in erasure_layout.c makes a call to get_flash_region(). This call happens after erase layout is calculated, however get_flash_region() can potentially return smaller region.
Issue needs research (and fix if needed).
Originally reported by Vincent Fazio, copying the report below:
As part of looking over #1 and #2, I developed some slight concerns about the loop on line 314 which is separate from
this patchset. I don't know if it warrants an issue and further discussion, and I haven't spelunked into the erase function
selection logic, but the concern I have there is we've already pre-calculated what erase functions we're using but
`get_flash_region` could return a region with a shorter end range, meaning the selected erase block fn could erase part
of the next region. So if we had a 32k erase block fn, it seems like if region.end forces the length of the erasable region
to 4k, we don't actually select a 4k erase function and instead continue to use a 32k function. If the next region is write
protected it seems like we'd have verification errors.
I think this currently only affects masters that have get_region defined, so `opaque_master_ich_hwseq` is at risk here.
This may have been less of a risk with the legacy path because, from what I remember, it always used the smallest working
erase block function, however the new path adjusts the function used based on the amount of changed data and coalesces blocks
when possible (I think).
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