Fixes for GHSA-88jx-383q-w4qc and GHSA-95pr-fxf5-86gv #3661
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An Image may come from an untrusted source and contain an unknown number of signatures in the .sig manifest. A common pattern in cosign is to use the number of signatures as the capacity for a new slice. But this means the size of the slice is based on an unvalidated external input and could result in cosign running out of memory. This change adds validation for certain implementations of the oci.Signatures Get() method to limit the number of image descriptors returned. This way, callers can rely on the returned slice of signatures being a reasonable size to process safely. The limit is set to 1000, which is a generous size based on the practical restrictions that container registries set for image manifest size and approximations of memory allocations for signature layers. Signed-off-by: Colleen Murphy <colleenmurphy@google.com> Co-authored-by: Colleen Murphy <colleenmurphy@google.com>
When downloading an attestation or SBOM from an external source, check its size before reading it into memory. This protects the host from potentially reading a maliciously large attachment into memory and exhausting the system. SBOMs can vary widely in size, and there could be legitimate SBOMs of up to 700MB. However, reading a 700MB SBOM into memory would easily bring down a small cloud VM. Moreover, most SBOMs are not going to be that large. This change sets a reasonable default of 128MiB, and allows overriding the default by setting the environment variable `COSIGN_MAX_ATTACHMENT_SIZE`. Signed-off-by: Colleen Murphy <colleenmurphy@google.com> Co-authored-by: Colleen Murphy <colleenmurphy@google.com>
Signed-off-by: Hayden Blauzvern <hblauzvern@google.com>
bobcallaway
approved these changes
Apr 10, 2024
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Summary
Release Note
Documentation