From 2612dcfd3cb6dd73c76e14a24fe1a68e2708e4e3 Mon Sep 17 00:00:00 2001 From: Damien Neil Date: Thu, 11 Sep 2025 13:32:10 -0700 Subject: [PATCH] [release-branch.go1.25] archive/tar: set a limit on the size of GNU sparse file 1.0 regions Sparse files in tar archives contain only the non-zero components of the file. There are several different encodings for sparse files. When reading GNU tar pax 1.0 sparse files, archive/tar did not set a limit on the size of the sparse region data. A malicious archive containing a large number of sparse blocks could cause archive/tar to read an unbounded amount of data from the archive into memory. Since a malicious input can be highly compressable, a small compressed input could cause very large allocations. Cap the size of the sparse block data to the same limit used for PAX headers (1 MiB). Thanks to Harshit Gupta (Mr HAX) (https://www.linkedin.com/in/iam-harshit-gupta/) for reporting this issue. Fixes CVE-2025-58183 For #75677 Fixes #75711 Change-Id: I70b907b584a7b8676df8a149a1db728ae681a770 Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/2800 Reviewed-by: Roland Shoemaker Reviewed-by: Nicholas Husin Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/2987 Reviewed-by: Damien Neil Reviewed-on: https://go-review.googlesource.com/c/go/+/709852 TryBot-Bypass: Michael Pratt Reviewed-by: Carlos Amedee Auto-Submit: Michael Pratt --- src/archive/tar/common.go | 1 + src/archive/tar/reader.go | 9 +++++++-- src/archive/tar/reader_test.go | 5 +++++ .../tar/testdata/gnu-sparse-many-zeros.tar.bz2 | Bin 0 -> 1642 bytes 4 files changed, 13 insertions(+), 2 deletions(-) create mode 100644 src/archive/tar/testdata/gnu-sparse-many-zeros.tar.bz2 diff --git a/src/archive/tar/common.go b/src/archive/tar/common.go index 7b3945ff15..ad31bbb64a 100644 --- a/src/archive/tar/common.go +++ b/src/archive/tar/common.go @@ -39,6 +39,7 @@ var ( errMissData = errors.New("archive/tar: sparse file references non-existent data") errUnrefData = errors.New("archive/tar: sparse file contains unreferenced data") errWriteHole = errors.New("archive/tar: write non-NUL byte in sparse hole") + errSparseTooLong = errors.New("archive/tar: sparse map too long") ) type headerError []string diff --git a/src/archive/tar/reader.go b/src/archive/tar/reader.go index 8483fb52a2..16ac2f5b17 100644 --- a/src/archive/tar/reader.go +++ b/src/archive/tar/reader.go @@ -531,12 +531,17 @@ func readGNUSparseMap1x0(r io.Reader) (sparseDatas, error) { cntNewline int64 buf bytes.Buffer blk block + totalSize int ) // feedTokens copies data in blocks from r into buf until there are // at least cnt newlines in buf. It will not read more blocks than needed. feedTokens := func(n int64) error { for cntNewline < n { + totalSize += len(blk) + if totalSize > maxSpecialFileSize { + return errSparseTooLong + } if _, err := mustReadFull(r, blk[:]); err != nil { return err } @@ -569,8 +574,8 @@ func readGNUSparseMap1x0(r io.Reader) (sparseDatas, error) { } // Parse for all member entries. - // numEntries is trusted after this since a potential attacker must have - // committed resources proportional to what this library used. + // numEntries is trusted after this since feedTokens limits the number of + // tokens based on maxSpecialFileSize. if err := feedTokens(2 * numEntries); err != nil { return nil, err } diff --git a/src/archive/tar/reader_test.go b/src/archive/tar/reader_test.go index 99340a3047..fca53dae74 100644 --- a/src/archive/tar/reader_test.go +++ b/src/archive/tar/reader_test.go @@ -621,6 +621,11 @@ func TestReader(t *testing.T) { }, Format: FormatPAX, }}, + }, { + // Small compressed file that uncompresses to + // a file with a very large GNU 1.0 sparse map. + file: "testdata/gnu-sparse-many-zeros.tar.bz2", + err: errSparseTooLong, }} for _, v := range vectors { diff --git a/src/archive/tar/testdata/gnu-sparse-many-zeros.tar.bz2 b/src/archive/tar/testdata/gnu-sparse-many-zeros.tar.bz2 new file mode 100644 index 0000000000000000000000000000000000000000..751d7fd4b68be1a7439413b4089dbbde33a2900a GIT binary patch literal 1642 zcmZ>Y%CIzaj8qGb%wCwXiS2H0{DC_Y9GL$z2|RUTNGrcrz`)SKVZdrPcO01{ps1pvVeGD$*OEWa_73ksV;zBwoQh0BPEH%vtSITeAlMvtlB3E`^y)8{ zw~&+g8{-?Ahs_oW3u(QcHog6FpP~f~~=z-9g zf_wTZ7^XHZn&-}Zc8R{Fft9C2PEyk*pJkiw?fk^YcK6r>1_p%&1_y>jhFQI$94?0z za?Cl(nljTjt?TS76W-mu3JeU63=9nnhZs#ILKKBvodhkrxK0|)I$ibrgoSju6wr@N z42%qnElgP^KzXhfrD74$NvWo@w9QvsFnedxz`)4Dz{J4J!Ez-rpv4zx#WM|Ul~dWe zujeZ~$i0&Z3?dE&76vu}&J`B}T70wwI?n`zc}}^OvF6@lhub?YF)*+QFmN#NCX1lVw7II6Iq$It1A~AA zg93v=gRdLVZlD!@quw8l{n5lfn)hi|^v!SyiA^y0F{gnCT=X?DusWMCWpyr3vv&I) ZCg2!yghOkJkj3svnul7NKE7EI0RUq%CTjoy literal 0 HcmV?d00001 -- 2.52.0