From 33d725e5758bf1fea62e6c77fc70b57a828a49f5 Mon Sep 17 00:00:00 2001 From: Damien Neil Date: Tue, 14 May 2024 14:39:10 -0700 Subject: [PATCH] archive/zip: treat truncated EOCDR comment as an error When scanning for an end of central directory record, treat an EOCDR signature with a record containing a truncated comment as an error. Previously, we would skip over the invalid record and look for another one. Other implementations do not do this (they either consider this a hard error, or just ignore the truncated comment). This parser misalignment allowed presenting entirely different archive contents to Go programs and other zip decoders. Fixes #66869 Change-Id: I94e5cb028534bb5704588b8af27f1e22ea49c7c6 Reviewed-on: https://go-review.googlesource.com/c/go/+/585397 Reviewed-by: Joseph Tsai Reviewed-by: Dmitri Shuralyov LUCI-TryBot-Result: Go LUCI --- src/archive/zip/reader.go | 8 ++++++-- src/archive/zip/reader_test.go | 8 ++++++++ src/archive/zip/testdata/comment-truncated.zip | Bin 0 -> 216 bytes 3 files changed, 14 insertions(+), 2 deletions(-) create mode 100644 src/archive/zip/testdata/comment-truncated.zip diff --git a/src/archive/zip/reader.go b/src/archive/zip/reader.go index ff6fedf632a09e..60b34b76ee63cc 100644 --- a/src/archive/zip/reader.go +++ b/src/archive/zip/reader.go @@ -699,9 +699,13 @@ func findSignatureInBlock(b []byte) int { if b[i] == 'P' && b[i+1] == 'K' && b[i+2] == 0x05 && b[i+3] == 0x06 { // n is length of comment n := int(b[i+directoryEndLen-2]) | int(b[i+directoryEndLen-1])<<8 - if n+directoryEndLen+i <= len(b) { - return i + if n+directoryEndLen+i > len(b) { + // Truncated comment. + // Some parsers (such as Info-ZIP) ignore the truncated comment + // rather than treating it as a hard error. + return -1 } + return i } } return -1 diff --git a/src/archive/zip/reader_test.go b/src/archive/zip/reader_test.go index 9f651da53070a6..00e5ec3e058610 100644 --- a/src/archive/zip/reader_test.go +++ b/src/archive/zip/reader_test.go @@ -570,6 +570,14 @@ var tests = []ZipTest{ }, }, }, + // Issue 66869: Don't skip over an EOCDR with a truncated comment. + // The test file sneakily hides a second EOCDR before the first one; + // previously we would extract one file ("file") from this archive, + // while most other tools would reject the file or extract a different one ("FILE"). + { + Name: "comment-truncated.zip", + Error: ErrFormat, + }, } func TestReader(t *testing.T) { diff --git a/src/archive/zip/testdata/comment-truncated.zip b/src/archive/zip/testdata/comment-truncated.zip new file mode 100644 index 0000000000000000000000000000000000000000..1bc19a85575964f378a8a30f198ed6ba5360aa7d GIT binary patch literal 216 zcmWIWW@cf4gUWrGI~jpI5C#dmdHT2ppr}ax{CO=%28Pozb5c_hOA-UT8JU2>aDc83 pE&*nMbOm^`vVk~^KxhP{)xa|7=AgR>tO!m(+=pt;1fVP<0{|c)7RUeq literal 0 HcmV?d00001