Ubuntu
libuv1 package

libuv1 calls readlink() with buffer size zero for /proc/self (nodejs test-case failure on s390x and LXD)

Bug #1792647 reported by Mauricio Faria de Oliveira on 2018-09-14

This bug affects 1 person

Affects		Status	Importance	Assigned to	Milestone
	libuv1 (Ubuntu)	Fix Released	Undecided	Mauricio Faria de Oliveira

Bug Description

The Debian patch 'path_max' causes failures when
readlink'ing symlinks that involve /proc/self
(and potentially other symlinks in /proc)
which report st_size == 0.

It uses st_size as a buffer size for readlink(),
which then fails with EINVAL.

This breaks the nodejs test-case test-fs-realpath-pipe.js
on s390x and LXD containers (which symlink /dev/stdin
to /proc/self/fd/0 vs. fd/0 as in amd64 non-container):

$ strace -E LD_LIBRARY_PATH=/usr/local/lib/ -f -e lstat,readlink \
node test/parallel/test-fs-realpath-pipe.js

    [pid 17785] lstat("/dev", {st_mode=S_IFDIR|0755, st_size=480, ...}) = 0
    [pid 17786] lstat("/dev/stdin", {st_mode=S_IFLNK|0777, st_size=15, ...}) = 0
    [pid 17788] lstat("/dev/stdin", {st_mode=S_IFLNK|0777, st_size=15, ...}) = 0
    [pid 17788] readlink("/dev/stdin", "/proc/self/fd/0", 15) = 15

    [pid 17785] lstat("/proc", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
    [pid 17786] lstat("/proc/self", {st_mode=S_IFLNK|0777, st_size=0, ...}) = 0
    [pid 17788] lstat("/proc/self", {st_mode=S_IFLNK|0777, st_size=0, ...}) = 0
    [pid 17788] readlink("/proc/self", 0x7f2a6c000b40, 0) = -1 EINVAL (Invalid argument)

I'll submit a patch shortly.

Tags:

Revision history for this message

Mauricio Faria de Oliveira (mfo) wrote on 2018-09-14:

This has been verified on a PPA to resolve the nodejs test-case failure on s390x.

Revision history for this message

Mauricio Faria de Oliveira (mfo) wrote on 2018-09-14:

This also fixes the problem in LXD on amd64:

Before:

$ node test/parallel/test-fs-realpath-pipe.js
assert.js:42
throw new errors.AssertionError({
^

AssertionError [ERR_ASSERTION]: 1 === 2
    at Object.<anonymous> (/home/ubuntu/nodejs-8.11.2~dfsg/test/parallel/test-fs-realpath-pipe.js:44:10)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Function.Module.runMain (module.js:693:10)
    at startup (bootstrap_node.js:191:16)
    at bootstrap_node.js:612:3

After:

$ wget https://launchpad.net/~mfo/+archive/ubuntu/sf189591-s390x-2/+files/libuv1_1.22.0-3ubuntu1_amd64.deb
$ sudo dpkg -i libuv1_1.22.0-3ubuntu1_amd64.deb

$ node test/parallel/test-fs-realpath-pipe.js
$

Revision history for this message

Ubuntu Foundations Team Bug Bot (crichton) wrote on 2018-09-15:

The attachment "libuv1-path_max_zero_st_size.debdiff" seems to be a debdiff. The ubuntu-sponsors team has been subscribed to the bug report so that they can review and hopefully sponsor the debdiff. If the attachment isn't a patch, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are member of the ~ubuntu-sponsors, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issue please contact him.]

tags:

added: patch

Mauricio Faria de Oliveira (mfo) on 2018-09-17

summary:

- fix nodejs test-case failure on s390x and LXD
+ libuv1 calls readlink() with buffer size zero for /proc/self (nodejs
+ test-case failure on s390x and LXD)

Revision history for this message

Mauricio Faria de Oliveira (mfo) wrote on 2018-09-17:

libuv1-path_max_zero_st_size.debdiff Edit (5.5 KiB, text/plain)

This is the same debdiff for Cosmic, now updated with Bug-Ubuntu and Bug-Debian tags (BTS 909011).

Revision history for this message

Mauricio Faria de Oliveira (mfo) wrote on 2018-09-18:

This is applied in cosmic-proposed, version 1.22.0-3ubuntu1. Thanks!

Changed in libuv1 (Ubuntu):
status:	New → Fix Committed
assignee:	nobody → Mauricio Faria de Oliveira (mfo)

Revision history for this message

Launchpad Janitor (janitor) wrote on 2018-09-18:

This bug was fixed in the package libuv1 - 1.22.0-3ubuntu1

---------------
libuv1 (1.22.0-3ubuntu1) cosmic; urgency=medium

  * debian/patches/path_max_zero_st_size: fix buffer size of zero
    for readlink() (EINVAL) when lstat() reports st_size == 0.
    This fixes nodejs test-case parallel/test-fs-realpath-pipe.js
    on s390x and in LXD on amd64. (LP: #1792647)

-- Mauricio Faria de Oliveira <email address hidden> Fri, 14 Sep 2018 19:27:12 -0300