4.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@google.com
commit 81a7be2cd69b412ab6aeacfe5ebf1bb6e5bce955 upstream.
asn1_ber_decoder() was ignoring errors from actions associated with the opcodes ASN1_OP_END_SEQ_ACT, ASN1_OP_END_SET_ACT, ASN1_OP_END_SEQ_OF_ACT, and ASN1_OP_END_SET_OF_ACT. In practice, this meant the pkcs7_note_signed_info() action (since that was the only user of those opcodes). Fix it by checking for the error, just like the decoder does for actions associated with the other opcodes.
This bug allowed users to leak slab memory by repeatedly trying to add a specially crafted "pkcs7_test" key (requires CONFIG_PKCS7_TEST_KEY).
In theory, this bug could also be used to bypass module signature verification, by providing a PKCS#7 message that is misparsed such that a signature's ->authattrs do not contain its ->msgdigest. But it doesn't seem practical in normal cases, due to restrictions on the format of the ->authattrs.
Fixes: 42d5ec27f873 ("X.509: Add an ASN.1 decoder") Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: David Howells dhowells@redhat.com Reviewed-by: James Morris james.l.morris@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- lib/asn1_decoder.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/lib/asn1_decoder.c +++ b/lib/asn1_decoder.c @@ -438,6 +438,8 @@ next_op: else act = machine[pc + 1]; ret = actions[act](context, hdr, 0, data + tdp, len); + if (ret < 0) + return ret; } pc += asn1_op_lengths[op]; goto next_op;