Instead of
```
#if CONDITION
for(XXX)
for(YYY)
#else
for(XXX)
for(YYY)
#endif
BODY
```
duplicate the BODY code. This isn't ideal, but we can live with it.
The compelling reason to restructure the code is that this entanglement
of C preprocessor syntax with C grammar syntax confuses uncrustify.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
psa_cipher_encrypt() and psa_cipher_decrypt() sometimes add a zero offset to
a null pointer when the cipher does not use an IV. This is undefined
behavior, although it works as naively expected on most platforms. This
can cause a crash with modern Clang+ASan (depending on compiler optimizations).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
When x is the most negative value of a two's complement type,
`(unsigned_type)(-x)` has undefined behavior, whereas `-(unsigned_type)x`
has well-defined behavior and does what was intended.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Fix undefined behavior (typically harmless in practice) of
mbedtls_mpi_add_mpi(), mbedtls_mpi_add_abs() and mbedtls_mpi_add_int() when
both operands are 0 and the left operand is represented with 0 limbs.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
In mbedtls_mpi_add_mpi() and mbedtls_mpi_sub_mpi(), and by extention
mbedtls_mpi_add_int() and mbedtls_mpi_sub_int(), when the resulting value
was zero, the sign bit of the result was incorrectly set to -1 when the
left-hand operand was negative. This is not a valid mbedtls_mpi
representation. Fix this: always set the sign to +1 when the result is 0.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
mbedtls_mpi_add_mpi() and mbedtls_mpi_sub_mpi() have the same logic, just
with one bit to flip in the sign calculation. Move the shared logic to a new
auxiliary function. This slightly reduces the code size (if the compiler
doesn't inline) and reduces the maintenance burden.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The transport is allowed to be MBEDTLS_SSL_TRANSPORT_DATAGRAM when the
compression is MBEDTLS_SSL_COMPRESS_NULL.
Signed-off-by: David Horstmann <david.horstmann@arm.com>
Change is_compression_ok() to is_compression_bad() for more semantics
that are a better match for what's really going on in the case of no
compression support.
Signed-off-by: David Horstmann <david.horstmann@arm.com>
The bit length of m is leaked through through timing in ecp_mul_mxz().
Initially found by Manuel Pégourié-Gonnard on ecp_mul_edxyz(), which has
been inspired from ecp_mul_mxz(), during initial review of the EdDSA PR.
See: https://github.com/Mbed-TLS/mbedtls/pull/3245#discussion_r490827996
Fix that by using grp->nbits + 1 instead, which anyway is very close to
the length of m, which means there is no significant performance impact.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
