On 2021-08-17 3:37 a.m., Jim Meyering wrote:
On Tue, Aug 17, 2021 at 2:02 AM Pádraig Brady <p...@draigbrady.com> wrote:
On 16/08/2021 22:17, Assaf Gordon wrote:
Attached a suggested fix.
minor nit in NEWS:
a nit in the commit log:
Thanks, attached updated patch.
Will push this week if there are no other comments.
-assaf
>From 090663068a23662b36ddc0603fc1c2c752b6aff1 Mon Sep 17 00:00:00 2001
From: Assaf Gordon <assafgor...@gmail.com>
Date: Mon, 16 Aug 2021 15:03:36 -0600
Subject: [PATCH] basenc: fix bug49741: using wrong decoding buffer length
Emil Lundberg <lundberg.e...@gmail.com> reports in
https://bugs.gnu.org/49741 about a 'basenc --base64 -d' decoding bug.
The input buffer length was not divisible by 3, resulting in
decoding errors.
* NEWS: Mention fix.
* src/basenc.c (DEC_BLOCKSIZE): Change from 1024*5 to 4200 (35*3*5*8)
which is divisible by 3,4,5,8 - satisfying both base32 and base64;
Use compile-time verify() macro to enforce the above.
* tests/misc/basenc.pl: Add test.
---
NEWS | 4 ++++
src/basenc.c | 4 +++-
tests/misc/basenc.pl | 9 +++++++++
3 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/NEWS b/NEWS
index ddec56bdf..efdb1450e 100644
--- a/NEWS
+++ b/NEWS
@@ -60,6 +60,10 @@ GNU coreutils NEWS -*- outline -*-
invalid combinations of case character classes.
[bug introduced in coreutils-8.6]
+ basenc --base64 --decode no longer silently discards decoded characters
+ on (1024*5) buffer boundaries
+ [bug introduced in coreutils-8.31]
+
** Changes in behavior
cp and install now default to copy-on-write (COW) if available.
diff --git a/src/basenc.c b/src/basenc.c
index 5c97a3652..2ffdb2d27 100644
--- a/src/basenc.c
+++ b/src/basenc.c
@@ -213,7 +213,9 @@ verify (DEC_BLOCKSIZE % 12 == 0); /* So complete encoded blocks are used. */
/* Note that increasing this may decrease performance if --ignore-garbage
is used, because of the memmove operation below. */
-# define DEC_BLOCKSIZE (1024*5)
+# define DEC_BLOCKSIZE (4200)
+verify (DEC_BLOCKSIZE % 40 == 0); /* complete encoded blocks for base32 */
+verify (DEC_BLOCKSIZE % 12 == 0); /* complete encoded blocks for base64 */
static int (*base_length) (int i);
static bool (*isbase) (char ch);
diff --git a/tests/misc/basenc.pl b/tests/misc/basenc.pl
index 3383aaeef..ac5394731 100755
--- a/tests/misc/basenc.pl
+++ b/tests/misc/basenc.pl
@@ -37,6 +37,13 @@ my $base64url_out_nl = $base64url_out;
$base64url_out_nl =~ s/(..)/\1\n/g; # add newline every two characters
+# Bug 49741:
+# The input is 'abc' in base64, in an 8K buffer (larger than 1024*5,
+# the buffer size which caused the bug).
+my $base64_bug49741_in = "YWJj" x 2000 ;
+my $base64_bug49741_out = "abc" x 2000 ;
+
+
my $base32_in = "\xfd\xd8\x07\xd1\xa5";
my $base32_out = "7XMAPUNF";
my $x = $base32_out;
@@ -111,6 +118,8 @@ my @Tests =
['b64u_7', '--base64url -d', {IN=>$base64_out},
{EXIT=>1}, {ERR=>"$prog: invalid input\n"}],
+ ['b64_bug49741', '--base64 -d', {IN=>$base64_bug49741_in},
+ {OUT=>$base64_bug49741_out}],
--
2.20.1
