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sae: fix potential infinite loop

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It was assumed that the hunt-and-peck loop was guarenteed to find
a PWE. This was incorrect in terms of kernel support. If a system
does not have support for AF_ALG or runs out of file descriptors
the KDFs may fail. The loop continued to run if found == false,
which is also incorrect because we want to stop after 20 iterations
regarless of success.

This changes the loop to a for loop so it will always exit after
the set number of iterations.
This commit is contained in:
James Prestwood 2019-04-04 09:03:16 -07:00 committed by Denis Kenzior
parent 23041a44dd
commit c985da04ca
1 changed files with 3 additions and 7 deletions
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10
src/sae.c
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@ -251,8 +251,7 @@ static bool sae_compute_pwe(struct sae_sm *sm, char *password,
const uint8_t *addr1, const uint8_t *addr2) const uint8_t *addr1, const uint8_t *addr2)
{ {
bool found = false; bool found = false;
uint8_t counter = 1; uint8_t counter;
uint8_t k = 20;
uint8_t pwd_seed[32]; uint8_t pwd_seed[32];
struct l_ecc_scalar *pwd_value; struct l_ecc_scalar *pwd_value;
uint8_t random[32]; uint8_t random[32];
@ -267,7 +266,7 @@ static bool sae_compute_pwe(struct sae_sm *sm, char *password,
qr = sae_new_residue(sm->curve, true); qr = sae_new_residue(sm->curve, true);
qnr = sae_new_residue(sm->curve, false); qnr = sae_new_residue(sm->curve, false);
do { for (counter = 1; counter <= 20; counter++) {
/* pwd-seed = H(max(addr1, addr2) || min(addr1, addr2), /* pwd-seed = H(max(addr1, addr2) || min(addr1, addr2),
* base || counter) * base || counter)
* pwd-value = KDF-256(pwd-seed, "SAE Hunting and Pecking", p) * pwd-value = KDF-256(pwd-seed, "SAE Hunting and Pecking", p)
@ -291,10 +290,7 @@ static bool sae_compute_pwe(struct sae_sm *sm, char *password,
} }
l_ecc_scalar_free(pwd_value); l_ecc_scalar_free(pwd_value);
}
counter++;
} while ((counter <= k) || (found == false));
l_ecc_scalar_free(qr); l_ecc_scalar_free(qr);
l_ecc_scalar_free(qnr); l_ecc_scalar_free(qnr);