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Merge branch 'update/mbedtls_mpi_assert' into 'master'

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fix(mbedtls): Update redundant assert for H/W MPI operations

See merge request espressif/esp-idf!24922
This commit is contained in:
Mahavir Jain 2023-07-28 13:16:02 +08:00
commit 89c7608f05
1 changed files with 9 additions and 5 deletions
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14
components/mbedtls/port/bignum/esp_bignum.c
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@ -631,11 +631,14 @@ static int mpi_mult_mpi_failover_mod_mult( mbedtls_mpi *Z, const mbedtls_mpi *X,
mpi_hal_read_result_hw_op(Z->MBEDTLS_PRIVATE(p), Z->MBEDTLS_PRIVATE(n), hw_words);
Z->MBEDTLS_PRIVATE(s) = X->MBEDTLS_PRIVATE(s) * Y->MBEDTLS_PRIVATE(s);
/*
* Relevant: https://github.com/espressif/esp-idf/issues/11850
* If the first condition fails then most likely hardware peripheral
* has produced an incorrect result for MPI operation. This can
* happen if data fed to the peripheral register was incorrect.
*
* If z_words < mpi_words(Z) (the actual words taken by the MPI result),
* the assert fails due to unsigned arithmetic - most likely hardware
* peripheral has produced an incorrect result for MPI operation.
* This can happen if data fed to the peripheral register was incorrect.
*
* z_words is calculated as the worst-case possible size of the result
* MPI Z. The difference between z_words and the actual words taken by
@ -646,9 +649,10 @@ static int mpi_mult_mpi_failover_mod_mult( mbedtls_mpi *Z, const mbedtls_mpi *X,
* 0b1111 * 0b1111 = 0b11100001 -> 8 bits
* 0b1000 * 0b1000 = 0b01000000 -> 7 bits.
* The code rounds up to the nearest word size, so the maximum difference
* could be of only 1 word. The second condition handles this.
* could be of only 1 word. The assert handles this.
*
*/
assert((z_words >= mpi_words(Z)) && (z_words - mpi_words(Z) <= (size_t)1));
assert(z_words - mpi_words(Z) <= (size_t)1);
cleanup:
esp_mpi_disable_hardware_hw_op();
return ret;