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fix: improve validation and and fix regression in tests

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Previous EoCD detection performance improvement changes in
https://github.com/0x5eal/luau-unzip/commit/b710e296 inadvertently fixed
some bugs to do with max size ZIP reads, which caused a regression in
the `invalid_cde_number_of_files_allocation_greater_offset.zip` test,
which used to error as expected due to out-of-bounds buffer reads. This
commit fixes this by improving size validations present in the methods
`ZipReader:parseEocdRecord` and `ZipReader:parseCentralDirectory`.
This commit is contained in:
Erica Marigold 2025-02-24 07:20:40 +00:00
parent 545de01536
commit 39009b734c
Signed by: DevComp
SSH key fingerprint: SHA256:jD3oMT4WL3WHPJQbrjC3l5feNCnkv7ndW8nYaHX5wFw
1 changed files with 14 additions and 2 deletions
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16
lib/init.luau
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@ -531,12 +531,18 @@ function ZipReader.parseEocdRecord(self: ZipReader, pos: number): EocdRecord
local cdSize = buffer.readu32(self.data, pos + 12)
local cdOffset = buffer.readu32(self.data, pos + 16)
-- Validate CD boundaries and entry count
-- Validate CD boundaries and entry count; Ensure minimum size is at least 30 bytes and
-- total size after the local header is not larger than the buffer size
local bufSize = buffer.len(self.data)
if cdOffset >= bufSize or cdOffset + cdSize > bufSize then
if cdOffset >= bufSize or cdOffset < 30 or cdOffset + cdSize > bufSize then
error("Invalid Central Directory offset or size")
end
-- Validate CD size range; min = 46 bytes per entry, max = 0xFFFF * 3 + 46 bytes per entry
if cdSize < cdEntries * 46 or cdEntries * (0xFFFF * 3 + 46) < cdSize then
error("Invalid Central Directory size for claimed number of entries")
end
local commentLength = buffer.readu16(self.data, pos + 20)
return {
diskNumber = buffer.readu16(self.data, pos + 4),
@ -609,6 +615,11 @@ function ZipReader.parseCentralDirectory(self: ZipReader): ()
local offset = buffer.readu32(self.data, pos + 42)
local name = buffer.readstring(self.data, pos + 46, nameLength)
local entrySize = 46 + nameLength + extraLength + commentLength
if pos + entrySize > record.cdOffset + record.cdSize then
error("Invalid Central Directory entry size")
end
table.insert(
self.entries,
ZipEntry.new(offset, name, {
@ -630,6 +641,7 @@ function ZipReader.parseCentralDirectory(self: ZipReader): ()
if entriesFound ~= record.cdEntries then
error("Found different entries than specified in Central Directory")
end
self.comment = record.comment
end