[otbn] Patch an error in the OTBN boot services program #27679
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nasahlpa
approved these changes
Jul 22, 2025
| * | ||
| * There is a bug in the OTBN boot services program loaded by ROM. There is a | ||
| * single instruction with mistakenly transposed operands which can affect the | ||
| * random share values. This bug DOES NOT affect the correctness of the OTBN |
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| * random share values. This bug DOES NOT affect the correctness of the OTBN | |
| * random share values. This bug DOES NOT affect the correctness of the OTBN |
| // Patch a bug in the OTBN ECDSA-P256 program. | ||
| // | ||
| // There is a single instruction with mistakenly transposed operands which | ||
| // can affect the random share values. This bug DOES NOT affect the |
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| // can affect the random share values. This bug DOES NOT affect the | |
| // can affect the random share values. This bug DOES NOT affect the |
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Are there any suggestions for testing this? |
IMO running the |
There is an error in the OTBN boot services program loaded by the ROM that can affect the random share values. This bug is caused by a simple transposition of operands in the `p256_base` source code. Since the OTBN program is stored in ROM and loaded into OTBN by the ROM, we patch it in the immutable section before we use that portion of the program. DO NOT cherrypick this change to the `master` branch. Signed-off-by: Chris Frantz <cfrantz@google.com>
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There is an error in the OTBN boot services program loaded by the ROM that can affect the random share values. This bug is caused by a simple transposition of operands in the
p256_basesource code.Since the OTBN program is stored in ROM and loaded into OTBN by the ROM, we patch it in the immutable section before we use that portion of the program.
DO NOT cherrypick this change to the
masterbranch.