On Sun, Mar 20, 2016 at 11:23:46PM +0100, Nicolai Stange wrote: > 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@xxxxxxxxx> Patch applied. Thanks! -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
