From 9a5467bf7b6e9e02ec9c3da4e23747c05faeaac6 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Tue, 5 Feb 2013 18:19:13 +0100 Subject: crypto: user - fix info leaks in report API Three errors resulting in kernel memory disclosure: 1/ The structures used for the netlink based crypto algorithm report API are located on the stack. As snprintf() does not fill the remainder of the buffer with null bytes, those stack bytes will be disclosed to users of the API. Switch to strncpy() to fix this. 2/ crypto_report_one() does not initialize all field of struct crypto_user_alg. Fix this to fix the heap info leak. 3/ For the module name we should copy only as many bytes as module_name() returns -- not as much as the destination buffer could hold. But the current code does not and therefore copies random data from behind the end of the module name, as the module name is always shorter than CRYPTO_MAX_ALG_NAME. Also switch to use strncpy() to copy the algorithm's name and driver_name. They are strings, after all. Signed-off-by: Mathias Krause Cc: Steffen Klassert Signed-off-by: Herbert Xu --- crypto/crypto_user.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) (limited to 'crypto/crypto_user.c') diff --git a/crypto/crypto_user.c b/crypto/crypto_user.c index 35d700a97d7..f6d9baf77f0 100644 --- a/crypto/crypto_user.c +++ b/crypto/crypto_user.c @@ -75,7 +75,7 @@ static int crypto_report_cipher(struct sk_buff *skb, struct crypto_alg *alg) { struct crypto_report_cipher rcipher; - snprintf(rcipher.type, CRYPTO_MAX_ALG_NAME, "%s", "cipher"); + strncpy(rcipher.type, "cipher", sizeof(rcipher.type)); rcipher.blocksize = alg->cra_blocksize; rcipher.min_keysize = alg->cra_cipher.cia_min_keysize; @@ -94,8 +94,7 @@ static int crypto_report_comp(struct sk_buff *skb, struct crypto_alg *alg) { struct crypto_report_comp rcomp; - snprintf(rcomp.type, CRYPTO_MAX_ALG_NAME, "%s", "compression"); - + strncpy(rcomp.type, "compression", sizeof(rcomp.type)); if (nla_put(skb, CRYPTOCFGA_REPORT_COMPRESS, sizeof(struct crypto_report_comp), &rcomp)) goto nla_put_failure; @@ -108,12 +107,14 @@ nla_put_failure: static int crypto_report_one(struct crypto_alg *alg, struct crypto_user_alg *ualg, struct sk_buff *skb) { - memcpy(&ualg->cru_name, &alg->cra_name, sizeof(ualg->cru_name)); - memcpy(&ualg->cru_driver_name, &alg->cra_driver_name, - sizeof(ualg->cru_driver_name)); - memcpy(&ualg->cru_module_name, module_name(alg->cra_module), - CRYPTO_MAX_ALG_NAME); - + strncpy(ualg->cru_name, alg->cra_name, sizeof(ualg->cru_name)); + strncpy(ualg->cru_driver_name, alg->cra_driver_name, + sizeof(ualg->cru_driver_name)); + strncpy(ualg->cru_module_name, module_name(alg->cra_module), + sizeof(ualg->cru_module_name)); + + ualg->cru_type = 0; + ualg->cru_mask = 0; ualg->cru_flags = alg->cra_flags; ualg->cru_refcnt = atomic_read(&alg->cra_refcnt); @@ -122,8 +123,7 @@ static int crypto_report_one(struct crypto_alg *alg, if (alg->cra_flags & CRYPTO_ALG_LARVAL) { struct crypto_report_larval rl; - snprintf(rl.type, CRYPTO_MAX_ALG_NAME, "%s", "larval"); - + strncpy(rl.type, "larval", sizeof(rl.type)); if (nla_put(skb, CRYPTOCFGA_REPORT_LARVAL, sizeof(struct crypto_report_larval), &rl)) goto nla_put_failure; -- cgit v1.2.3-18-g5258