From a06a6bf4e67a50561f6d6fb33534df1d3035ea34 Mon Sep 17 00:00:00 2001 From: Rishi Date: Wed, 15 Jul 2020 13:51:00 +0200 Subject: [PATCH] bpo-39017: Avoid infinite loop in the tarfile module (GH-21454) Avoid infinite loop when reading specially crafted TAR files using the tarfile module (CVE-2019-20907). (cherry picked from commit 5a8d121a1f3ef5ad7c105ee378cc79a3eac0c7d4) Co-authored-by: Rishi Removed testing 'recursion.tar' tar file due to binary data Upstream-Status: Backport [https://github.com/python/cpython/commit/c55479556db015f48fc8bbca17f64d3e65598559] CVE: CVE-2019-20907 Signed-off-by: Andrej Valek --- Lib/tarfile.py | 2 ++ .../2020-07-12-22-16-58.bpo-39017.x3Cg-9.rst | 1 + 4 files changed, 10 insertions(+) create mode 100644 Lib/test/recursion.tar create mode 100644 Misc/NEWS.d/next/Library/2020-07-12-22-16-58.bpo-39017.x3Cg-9.rst diff --git a/Lib/tarfile.py b/Lib/tarfile.py index d31b9cbb51d65..7a69e1b1aa544 100755 --- a/Lib/tarfile.py +++ b/Lib/tarfile.py @@ -1241,6 +1241,8 @@ def _proc_pax(self, tarfile): length, keyword = match.groups() length = int(length) + if length == 0: + raise InvalidHeaderError("invalid header") value = buf[match.end(2) + 1:match.start(1) + length - 1] # Normally, we could just use "utf-8" as the encoding and "strict" diff --git a/Misc/NEWS.d/next/Library/2020-07-12-22-16-58.bpo-39017.x3Cg-9.rst b/Misc/NEWS.d/next/Library/2020-07-12-22-16-58.bpo-39017.x3Cg-9.rst new file mode 100644 index 0000000000000..ad26676f8b856 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2020-07-12-22-16-58.bpo-39017.x3Cg-9.rst @@ -0,0 +1 @@ +Avoid infinite loop when reading specially crafted TAR files using the tarfile module (CVE-2019-20907).