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authorNicolai Stange <nicstange@gmail.com>2016-03-20 23:23:46 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2016-03-23 20:57:24 +0800
commite54358915d0a00399c11c2c23ae1be674cba188a (patch)
tree90890428938c11f630380f7cda818f6586f75e94
parentdfe97ad30e8c038261663a18b9e04b8b5bc07bea (diff)
downloadlinux-e54358915d0a00399c11c2c23ae1be674cba188a.tar.gz
PKCS#7: pkcs7_validate_trust(): initialize the _trusted output argument
Despite what the DocBook comment to pkcs7_validate_trust() says, the *_trusted argument is never set to false. pkcs7_validate_trust() only positively sets *_trusted upon encountering a trusted PKCS#7 SignedInfo block. This is quite unfortunate since its callers, system_verify_data() for example, depend on pkcs7_validate_trust() clearing *_trusted on non-trust. Indeed, UBSAN splats when attempting to load the uninitialized local variable 'trusted' from system_verify_data() in pkcs7_validate_trust(): UBSAN: Undefined behaviour in crypto/asymmetric_keys/pkcs7_trust.c:194:14 load of value 82 is not a valid value for type '_Bool' [...] Call Trace: [<ffffffff818c4d35>] dump_stack+0xbc/0x117 [<ffffffff818c4c79>] ? _atomic_dec_and_lock+0x169/0x169 [<ffffffff8194113b>] ubsan_epilogue+0xd/0x4e [<ffffffff819419fa>] __ubsan_handle_load_invalid_value+0x111/0x158 [<ffffffff819418e9>] ? val_to_string.constprop.12+0xcf/0xcf [<ffffffff818334a4>] ? x509_request_asymmetric_key+0x114/0x370 [<ffffffff814b83f0>] ? kfree+0x220/0x370 [<ffffffff818312c2>] ? public_key_verify_signature_2+0x32/0x50 [<ffffffff81835e04>] pkcs7_validate_trust+0x524/0x5f0 [<ffffffff813c391a>] system_verify_data+0xca/0x170 [<ffffffff813c3850>] ? top_trace_array+0x9b/0x9b [<ffffffff81510b29>] ? __vfs_read+0x279/0x3d0 [<ffffffff8129372f>] mod_verify_sig+0x1ff/0x290 [...] The implication is that pkcs7_validate_trust() effectively grants trust when it really shouldn't have. Fix this by explicitly setting *_trusted to false at the very beginning of pkcs7_validate_trust(). Cc: <stable@vger.kernel.org> Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
-rw-r--r--crypto/asymmetric_keys/pkcs7_trust.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c
index 90d6d47965b0..ecdb5a2ce085 100644
--- a/crypto/asymmetric_keys/pkcs7_trust.c
+++ b/crypto/asymmetric_keys/pkcs7_trust.c
@@ -178,6 +178,8 @@ int pkcs7_validate_trust(struct pkcs7_message *pkcs7,
int cached_ret = -ENOKEY;
int ret;
+ *_trusted = false;
+
for (p = pkcs7->certs; p; p = p->next)
p->seen = false;