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Handle odd buffer lengths in checksum

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Buffers of odd length can be passed to the checksum, for example signatures.
csum_bytes uses a uint16_t so change the function to prevent overflowing the
buffer, while taking the extra byte into account if the length is odd.

Signed-off-by: Linn Crosetto <linn@hpe.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
This commit is contained in:
Linn Crosetto 2015-10-27 15:31:12 -06:00 • committed by James Bottomley
parent 2c2f71313e
commit 1c9dfe7364
1 changed files with 7 additions and 4 deletions
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11
src/image.c
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@ -145,13 +145,16 @@ static uint16_t csum_update_fold(uint16_t csum, uint16_t x)
static uint16_t csum_bytes(uint16_t checksum, void *buf, size_t len) static uint16_t csum_bytes(uint16_t checksum, void *buf, size_t len)
{ {
unsigned int i; unsigned int i;
uint16_t *p; uint16_t *p = buf;
for (i = 0; i < len; i += sizeof(*p)) { for (i = 0; i + sizeof(*p) <= len; i += sizeof(*p)) {
p = buf + i; checksum = csum_update_fold(checksum, *p++);
checksum = csum_update_fold(checksum, *p);
} }
/* if length is odd, add the remaining byte */
if (i < len)
checksum = csum_update_fold(checksum, *((uint8_t *)p));
return checksum; return checksum;
} }