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Fix IAR warning about volatile access #10045

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Merged
douzzer merged 2 commits into from
Mar 30, 2026
Merged

Fix IAR warning about volatile access #10045

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b553e74
Fix IAR warning about volatile access
embhorn Mar 19, 2026
1a1bdb2
Address review feedback
embhorn Mar 25, 2026
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8 changes: 6 additions & 2 deletions src/internal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -41491,6 +41491,7 @@ static int DefTicketEncCb(WOLFSSL* ssl, byte key_name[WOLFSSL_TICKET_NAME_SZ],
{
RsaKey* key = (RsaKey*)ssl->hsKey;
volatile int lenErrMask;
int mask;

ret = RsaDec(ssl,
input + args->idx,
Expand All @@ -41517,8 +41518,11 @@ static int DefTicketEncCb(WOLFSSL* ssl, byte key_name[WOLFSSL_TICKET_NAME_SZ],
goto exit_dcke;

lenErrMask = 0 - (SECRET_LEN != args->sigSz);
args->lastErr = (ret & (~lenErrMask)) |
(WC_NO_ERR_TRACE(RSA_PAD_E) & lenErrMask);
/* Snapshot volatile to avoid multiple volatile
* accesses per expression. */
mask = lenErrMask;
args->lastErr = (ret & (~mask)) |
(WC_NO_ERR_TRACE(RSA_PAD_E) & mask);
ret = 0;
break;
} /* rsa_kea */
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18 changes: 13 additions & 5 deletions wolfcrypt/src/rsa.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1890,6 +1890,8 @@ static int RsaUnPad(const byte *pkcsBlock, unsigned int pkcsBlockLen,
volatile byte invalid = 0;
volatile byte minPad;
volatile int invalidMask;
byte inv;
word16 sep;

i = 0;
/* Decrypted with private key - unpad must be constant time. */
Expand All @@ -1900,18 +1902,24 @@ static int RsaUnPad(const byte *pkcsBlock, unsigned int pkcsBlockLen,
pastSep |= ctMask16Eq(pkcsBlock[j], 0x00);
}

/* Snapshot volatiles to avoid multiple volatile accesses per
* expression. */
inv = invalid;
sep = pastSep;

/* Minimum of 11 bytes of pre-message data - including leading 0x00. */
minPad = ctMaskLT(i, RSA_MIN_PAD_SZ);
invalid |= minPad;
inv |= minPad;
/* Must have seen separator. */
invalid |= (byte)~pastSep;
inv |= (byte)~sep;
/* First byte must be 0x00. */
invalid |= ctMaskNotEq(pkcsBlock[0], 0x00);
inv |= ctMaskNotEq(pkcsBlock[0], 0x00);
/* Check against expected block type: padValue */
invalid |= ctMaskNotEq(pkcsBlock[1], padValue);
inv |= ctMaskNotEq(pkcsBlock[1], padValue);

invalid = inv;
*output = (byte *)(pkcsBlock + i);
invalidMask = (int)-1 + (int)(invalid >> 7);
invalidMask = (int)-1 + (int)(inv >> 7);
ret = invalidMask & ((int)pkcsBlockLen - i);
}
#endif
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