Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 3.19.y-ckt 02/56] PKCS#7: pkcs7_validate_trust(): initialize the _trusted output argument | Date | Tue, 12 Apr 2016 13:58:20 -0700 |
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3.19.8-ckt19 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Nicolai Stange <nicstange@gmail.com>
commit e54358915d0a00399c11c2c23ae1be674cba188a upstream.
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().
Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- crypto/asymmetric_keys/pkcs7_trust.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c index 1d29376..841a04c 100644 --- a/crypto/asymmetric_keys/pkcs7_trust.c +++ b/crypto/asymmetric_keys/pkcs7_trust.c @@ -174,6 +174,8 @@ 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; -- 2.7.4
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