kris/boringssl
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

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

Browse Source 
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
crypto/rc4/rc4.c
View File

@ -141,37 +141,6 @@ void RC4(RC4_KEY *key, size_t len, const uint8_t *in, uint8_t *out) {
in += 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 */
#define LESHFT(c) (((c) * 8) & (sizeof(RC4_CHUNK) * 8 - 1))
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);
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) \