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Mind the end of the buffer in aligned case of generic RC4 implementation.

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The generic RC4 implementation may read and write just past the end of the
buffer; when input and output are aligned, it always reads an RC4_CHUNK at a
time. It appropriately masks off and preserves the excess bytes off the end, so
this can only have practical effects if it crosses a page boundary. There's an
alignment check, so that can't happen; page boundaries are always aligned. But
it makes ASan unhappy and strictly speaking is a memory error.

Instead, fall through to the generic codepath which just reads it byte by byte.
This should fix the other bot failure.

Change-Id: I3cbd3bfc6cb0537e87f3252dea12d40ffa78d590
Reviewed-on: https://boringssl-review.googlesource.com/4722
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
David Benjamin 2015-05-11 23:45:58 -04:00 committed by Adam Langley
parent 5694b3a84b
commit de12d6cd7a
1 changed files with 0 additions and 62 deletions
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62
crypto/rc4/rc4.c
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@ -141,37 +141,6 @@ void RC4(RC4_KEY *key, size_t len, const uint8_t *in, uint8_t *out) {
in += sizeof(RC4_CHUNK); in += sizeof(RC4_CHUNK);
out += sizeof(RC4_CHUNK); out += sizeof(RC4_CHUNK);
} }
if (len) {
RC4_CHUNK mask = (RC4_CHUNK) - 1, ochunk;
ichunk = *(RC4_CHUNK *)in;
ochunk = *(RC4_CHUNK *)out;
otp = 0;
i = BESHFT(0);
mask <<= (sizeof(RC4_CHUNK) - len) << 3;
switch (len & (sizeof(RC4_CHUNK) - 1)) {
case 7:
otp = RC4_STEP << i, i -= 8;
case 6:
otp |= RC4_STEP << i, i -= 8;
case 5:
otp |= RC4_STEP << i, i -= 8;
case 4:
otp |= RC4_STEP << i, i -= 8;
case 3:
otp |= RC4_STEP << i, i -= 8;
case 2:
otp |= RC4_STEP << i, i -= 8;
case 1:
otp |= RC4_STEP << i, i -= 8;
}
ochunk &= ~mask;
ochunk |= (otp ^ ichunk) & mask;
*(RC4_CHUNK *)out = ochunk;
}
key->x = x;
key->y = y;
return;
} else { /* LITTLE-ENDIAN CASE */ } else { /* LITTLE-ENDIAN CASE */
#define LESHFT(c) (((c) * 8) & (sizeof(RC4_CHUNK) * 8 - 1)) #define LESHFT(c) (((c) * 8) & (sizeof(RC4_CHUNK) * 8 - 1))
for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) { for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
@ -190,37 +159,6 @@ void RC4(RC4_KEY *key, size_t len, const uint8_t *in, uint8_t *out) {
in += sizeof(RC4_CHUNK); in += sizeof(RC4_CHUNK);
out += sizeof(RC4_CHUNK); out += sizeof(RC4_CHUNK);
} }
if (len) {
RC4_CHUNK mask = (RC4_CHUNK) - 1, ochunk;
ichunk = *(RC4_CHUNK *)in;
ochunk = *(RC4_CHUNK *)out;
otp = 0;
i = 0;
mask >>= (sizeof(RC4_CHUNK) - len) << 3;
switch (len & (sizeof(RC4_CHUNK) - 1)) {
case 7:
otp = RC4_STEP, i += 8;
case 6:
otp |= RC4_STEP << i, i += 8;
case 5:
otp |= RC4_STEP << i, i += 8;
case 4:
otp |= RC4_STEP << i, i += 8;
case 3:
otp |= RC4_STEP << i, i += 8;
case 2:
otp |= RC4_STEP << i, i += 8;
case 1:
otp |= RC4_STEP << i, i += 8;
}
ochunk &= ~mask;
ochunk |= (otp ^ ichunk) & mask;
*(RC4_CHUNK *)out = ochunk;
}
key->x = x;
key->y = y;
return;
} }
} }
#define LOOP(in, out) \ #define LOOP(in, out) \