Skip to content

[3.12] gh-113977, gh-120754: Remove unbounded reads from zipfile (GH-122101) #126347

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
gpshead merged 1 commit into from
Nov 3, 2024
Merged

[3.12] gh-113977, gh-120754: Remove unbounded reads from zipfile (GH-122101) #126347

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
gh-113977, gh-120754: Remove unbounded reads from zipfile (GH-122101) 
GH-113977, GH-120754: Remove unbounded reads from zipfile

Read without a size may read an unbounded amount of data + allocate
unbounded size buffers. Move to capped size reads to prevent potential
issues.

(cherry picked from commit 556dc9b)

Co-authored-by: Cody Maloney <cmaloney@users.noreply.github.com>
Co-authored-by: Daniel Hillier <daniel.hillier@gmail.com>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
  • Loading branch information
@cmaloney @danifus
@blurb-it @miss-islington
3 people authored and miss-islington committed Nov 3, 2024
commit 7ea6fd2ab2ed40217f6d4ceb0c4d655a179b66f0
6 changes: 3 additions & 3 deletions Lib/zipfile/__init__.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -295,7 +295,7 @@ def _EndRecData(fpin):
fpin.seek(-sizeEndCentDir, 2)
except OSError:
return None
data = fpin.read()
data = fpin.read(sizeEndCentDir)
if (len(data) == sizeEndCentDir and
data[0:4] == stringEndArchive and
data[-2:] == b"\000\000"):
Expand All @@ -315,9 +315,9 @@ def _EndRecData(fpin):
# record signature. The comment is the last item in the ZIP file and may be
# up to 64K long. It is assumed that the "end of central directory" magic
# number does not appear in the comment.
maxCommentStart = max(filesize - (1 << 16) - sizeEndCentDir, 0)
maxCommentStart = max(filesize - ZIP_MAX_COMMENT - sizeEndCentDir, 0)
fpin.seek(maxCommentStart, 0)
data = fpin.read()
data = fpin.read(ZIP_MAX_COMMENT + sizeEndCentDir)
start = data.rfind(stringEndArchive)
if start >= 0:
# found the magic number; attempt to unpack and interpret
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2024-07-23-02-24-50.gh-issue-120754.nHb5mG.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Update unbounded ``read`` calls in :mod:`zipfile` to specify an explicit ``size`` putting a limit on how much data they may read. This also updates handling around ZIP max comment size to match the standard instead of reading comments that are one byte too long.