crypto: caam - fix double-free in caam_rsa_set_priv_key_form()

caam_rsa_set_priv_key_form() frees the partially allocated key
components (p, q, tmp1, tmp2, dp, dq) with kfree_sensitive() on its
error path, but does not set those pointers to NULL afterward.

When the function returns an error, caam_rsa_set_priv_key() jumps to
its err label and calls caam_rsa_free_key(), which frees all of those
same pointers again, resulting in a double-free.

This is reachable when the allocation of q, tmp1, tmp2, dp, dq or qinv
fails, e.g. under memory pressure, or for a malformed key whose CRT
members decode to zero length and make caam_read_rsa_crt() return NULL.

Set each pointer to NULL right after freeing it so that the subsequent
caam_rsa_free_key() call becomes a no-op for the already-freed fields.

Fixes: 52e26d77b8b3 ("crypto: caam - add support for RSA key form 2")
Cc: stable@vger.kernel.org
Signed-off-by: ZhaoJinming <zhaojinming@uniontech.com>
Reviewed-by: Sahil Malhotra <sahil.malhotra@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/crypto/caam/caampkc.c b/drivers/crypto/caam/caampkc.c
index cb001aa1de66..ac515ed8c575 100644
--- a/drivers/crypto/caam/caampkc.c
+++ b/drivers/crypto/caam/caampkc.c
@@ -1033,16 +1033,22 @@ static int caam_rsa_set_priv_key_form(struct caam_rsa_ctx *ctx,
 
 free_dq:
 	kfree_sensitive(rsa_key->dq);
+	rsa_key->dq = NULL;
 free_dp:
 	kfree_sensitive(rsa_key->dp);
+	rsa_key->dp = NULL;
 free_tmp2:
 	kfree_sensitive(rsa_key->tmp2);
+	rsa_key->tmp2 = NULL;
 free_tmp1:
 	kfree_sensitive(rsa_key->tmp1);
+	rsa_key->tmp1 = NULL;
 free_q:
 	kfree_sensitive(rsa_key->q);
+	rsa_key->q = NULL;
 free_p:
 	kfree_sensitive(rsa_key->p);
+	rsa_key->p = NULL;
 	return -ENOMEM;
 }