deserialize: validate offsets for structs, slices, lists (zeam #843)#63
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ch4r10t33r wants to merge 1 commit intoblockblaz:masterfrom
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deserialize: validate offsets for structs, slices, lists (zeam #843)#63ch4r10t33r wants to merge 1 commit intoblockblaz:masterfrom
ch4r10t33r wants to merge 1 commit intoblockblaz:masterfrom
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Malformed peer-supplied SSZ could slice past the buffer and panic in struct second pass, variable []T decode, variable arrays, and List sszDecode. - Mirror array-deserializer guards: alignment, prefix in bounds, start/end ordering. - Struct: bounds-check fixed-field reads and variable-field slices; require first var offset to match fixed-prefix length. - Union: require non-empty payload before reading selector. - utils.List: fixed-size path rejects ragged length and count > N; dynamic path bounds-checks offset prefix. Adds regression tests for struct offsets past the buffer. Closes blockblaz/zeam#843 when consumed downstream.
g11tech
approved these changes
May 8, 2026
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Problem
Peer-supplied SSZ with invalid offset tables could slice past the buffer and panic during
deserialize(struct variable fields, variable[]T, variable arrays, andutils.Listdecode). See zeam#843.Change
start <= end, monotonic offsets.[]T: validate first/second offsets, item count, and each subsequent offset read before slicing.start <= end, offsets within buffer, monotonicity, andindices[0] == ifor the first variable field.serialized.len >= 1before reading the selector byte.utils.List.sszDecode: fixed-size items reject ragged length andn > N; dynamic path bounds-checks the offset-prefix length before slicing.Tests / tooling
build.zig.zon:minimum_zig_version = "0.16.0"(matches CI; satisfies anyzig when present).Downstream
After merge, zeam can switch from a vendored copy back to a
build.zig.zongit+dependency on the new commit.