From: Robbie Harwood <rharwood@xxxxxxxxxx> [ Upstream commit 4fc5c74dde69a7eda172514aaeb5a7df3600adb3 ] The PE Format Specification (section "The Attribute Certificate Table (Image Only)") states that `dwLength` is to be rounded up to 8-byte alignment when used for traversal. Therefore, the field is not required to be an 8-byte multiple in the first place. Accordingly, pesign has not performed this alignment since version 0.110. This causes kexec failure on pesign'd binaries with "PEFILE: Signature wrapper len wrong". Update the comment and relax the check. Signed-off-by: Robbie Harwood <rharwood@xxxxxxxxxx> Signed-off-by: David Howells <dhowells@xxxxxxxxxx> cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx> cc: Eric Biederman <ebiederm@xxxxxxxxxxxx> cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> cc: keyrings@xxxxxxxxxxxxxxx cc: linux-crypto@xxxxxxxxxxxxxxx cc: kexec@xxxxxxxxxxxxxxxxxxx Link: https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#the-attribute-certificate-table-image-only Link: https://github.com/rhboot/pesign Link: https://lore.kernel.org/r/20230220171254.592347-2-rharwood@xxxxxxxxxx/ # v2 Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- crypto/asymmetric_keys/verify_pefile.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c index 7553ab18db898..fe1bb374239d7 100644 --- a/crypto/asymmetric_keys/verify_pefile.c +++ b/crypto/asymmetric_keys/verify_pefile.c @@ -135,11 +135,15 @@ static int pefile_strip_sig_wrapper(const void *pebuf, pr_debug("sig wrapper = { %x, %x, %x }\n", wrapper.length, wrapper.revision, wrapper.cert_type); - /* Both pesign and sbsign round up the length of certificate table - * (in optional header data directories) to 8 byte alignment. + /* sbsign rounds up the length of certificate table (in optional + * header data directories) to 8 byte alignment. However, the PE + * specification states that while entries are 8-byte aligned, this is + * not included in their length, and as a result, pesign has not + * rounded up since 0.110. */ - if (round_up(wrapper.length, 8) != ctx->sig_len) { - pr_debug("Signature wrapper len wrong\n"); + if (wrapper.length > ctx->sig_len) { + pr_debug("Signature wrapper bigger than sig len (%x > %x)\n", + ctx->sig_len, wrapper.length); return -ELIBBAD; } if (wrapper.revision != WIN_CERT_REVISION_2_0) { -- 2.39.2
