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crypto: testmgr - add guard to dst buffer for ahash_export

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Add a guard to 'state' buffer and warn if its consistency after
call to crypto_ahash_export() changes, so that any write that
goes beyond advertised statesize (and thus causing potential
memory corruption [1]) is more visible.

[1] https://marc.info/?l=linux-crypto-vger&m=147467656516085

Signed-off-by: Jan Stancek <jstancek@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Marcelo Cerri <marcelo.cerri@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Jan Stancek 2016-09-28 16:38:37 +02:00 committed by Herbert Xu
parent 3387879524
commit 7bcb87bca2
1 changed files with 4 additions and 1 deletions
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5
crypto/testmgr.c
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@ -209,16 +209,19 @@ static int ahash_partial_update(struct ahash_request **preq,
char *state;
struct ahash_request *req;
int statesize, ret = -EINVAL;
const char guard[] = { 0x00, 0xba, 0xad, 0x00 };
req = *preq;
statesize = crypto_ahash_statesize(
crypto_ahash_reqtfm(req));
state = kmalloc(statesize, GFP_KERNEL);
state = kmalloc(statesize + sizeof(guard), GFP_KERNEL);
if (!state) {
pr_err("alt: hash: Failed to alloc state for %s\n", algo);
goto out_nostate;
}
memcpy(state + statesize, guard, sizeof(guard));
ret = crypto_ahash_export(req, state);
WARN_ON(memcmp(state + statesize, guard, sizeof(guard)));
if (ret) {
pr_err("alt: hash: Failed to export() for %s\n", algo);
goto out;