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Avoid mismatched comparison (suggested code improvement, not a bug!) #1114

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Avoid mismatched comparison (suggested code improvement, not a bug!) #1114

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f351d14
Avoid mismatched comparison (suggested code improvement, not a bug!)
nmouha May 12, 2026
b684cc5
fips202.c: introduce rsize to avoid mismatched comparison
nmouha May 12, 2026
2d7737d
fips202.c: fix indentation
nmouha May 12, 2026
7118e93
fips202x4.c: introduce rsize to avoid mismatched comparison
nmouha May 12, 2026
1e759cc
fips202.c: add source code comment
nmouha May 12, 2026
e8ebfa0
fips202x4.c: add source code comment
nmouha May 12, 2026
e0c8876
fips202.c: fix style
nmouha May 12, 2026
9c262f9
fips202x4.c: fix style
nmouha May 12, 2026
2025ff3
fips202.c: fix comment
nmouha May 12, 2026
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2 changes: 1 addition & 1 deletion mldsa/src/ct.h
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Original file line number Diff line number Diff line change
Expand Up @@ -299,7 +299,7 @@ __contract__(
ensures((return_value == 0) == forall(i, 0, len, (a[i] == b[i]))))
{
uint8_t r = 0, s = 0;
unsigned i;
size_t i;

for (i = 0; i < len; i++)
__loop__(
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10 changes: 7 additions & 3 deletions mldsa/src/fips202/fips202.c
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Expand Up @@ -77,7 +77,9 @@ __contract__(
assigns(memory_slice(s, sizeof(uint64_t) * MLD_KECCAK_LANES))
ensures(return_value < r))
{
while (inlen >= r - pos)
/* Safety: widen r to avoid type mismatch warning */
size_t rsize = r;
while (inlen >= rsize - pos)
__loop__(
assigns(pos, in, inlen,
memory_slice(s, sizeof(uint64_t) * MLD_KECCAK_LANES))
Expand Down Expand Up @@ -150,6 +152,8 @@ __contract__(
ensures(return_value <= r))
{
unsigned int i;
/* Safety: widen r to avoid type mismatch warning */
size_t rsize = r;
size_t out_offset = 0;

/* Reference: This code is re-factored from the reference implementation
Expand All @@ -174,8 +178,8 @@ __contract__(
mld_keccakf1600_permute(s);
pos = 0;
}
/* Safety: If bytes_to_go < r - pos, truncation to unsigned is safe. */
i = bytes_to_go < r - pos ? (unsigned)bytes_to_go : r - pos;
/* Safety: If bytes_to_go < rsize - pos, truncation to unsigned is safe. */
i = bytes_to_go < rsize - pos ? (unsigned)bytes_to_go : r - pos;
mld_keccakf1600_extract_bytes(s, out + out_offset, pos, i);
bytes_to_go -= i;
pos += i;
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6 changes: 4 additions & 2 deletions mldsa/src/fips202/fips202x4.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,9 @@ __contract__(
requires(memory_no_alias(in3, inlen))
assigns(memory_slice(s, sizeof(uint64_t) * MLD_KECCAK_LANES * MLD_KECCAK_WAY)))
{
while (inlen >= r)
/* Safety: widen r to avoid type mismatch warning */
size_t rsize = r;
while (inlen >= rsize)
__loop__(
assigns(inlen, in0, in1, in2, in3, memory_slice(s, sizeof(uint64_t) * MLD_KECCAK_LANES * MLD_KECCAK_WAY))
invariant(inlen <= loop_entry(inlen))
Expand All @@ -66,7 +68,7 @@ __contract__(
mld_keccakf1600x4_xor_bytes(s, in0, in1, in2, in3, 0, (unsigned)inlen);
}

if (inlen == r - 1)
if (inlen == rsize - 1)
{
p |= 128;
mld_keccakf1600x4_xor_bytes(s, &p, &p, &p, &p, (unsigned)inlen, 1);
Expand Down
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