67 lines
2.3 KiB
Diff
67 lines
2.3 KiB
Diff
From 709d1f8253072804cc27189a6f2b873d8d563399 Mon Sep 17 00:00:00 2001
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From: Assaf Gordon <assafgordon@gmail.com>
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Date: Mon, 16 Aug 2021 15:03:36 -0600
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Subject: [PATCH] basenc: fix bug49741: using wrong decoding buffer length
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Emil Lundberg <lundberg.emil@gmail.com> reports in
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https://bugs.gnu.org/49741 about a 'basenc --base64 -d' decoding bug.
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The input buffer length was not divisible by 3, resulting in
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decoding errors.
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* NEWS: Mention fix.
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* src/basenc.c (DEC_BLOCKSIZE): Change from 1024*5 to 4200 (35*3*5*8)
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which is divisible by 3,4,5,8 - satisfying both base32 and base64;
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Use compile-time verify() macro to enforce the above.
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* tests/misc/basenc.pl: Add test.
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---
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NEWS | 4 ++++
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src/basenc.c | 4 +++-
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tests/misc/basenc.pl | 9 +++++++++
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3 files changed, 16 insertions(+), 1 deletion(-)
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diff --git a/src/basenc.c b/src/basenc.c
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index 19a7b0aad..f4ca87267 100644
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--- a/src/basenc.c
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+++ b/src/basenc.c
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@@ -214,7 +214,9 @@ verify (DEC_BLOCKSIZE % 12 == 0); /* So complete encoded blocks are used. */
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/* Note that increasing this may decrease performance if --ignore-garbage
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is used, because of the memmove operation below. */
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-# define DEC_BLOCKSIZE (1024*5)
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+# define DEC_BLOCKSIZE (4200)
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+verify (DEC_BLOCKSIZE % 40 == 0); /* complete encoded blocks for base32 */
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+verify (DEC_BLOCKSIZE % 12 == 0); /* complete encoded blocks for base64 */
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static int (*base_length) (int i);
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static bool (*isbase) (char ch);
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diff --git a/tests/misc/basenc.pl b/tests/misc/basenc.pl
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index 3383aaeef..ac5394731 100755
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--- a/tests/misc/basenc.pl
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+++ b/tests/misc/basenc.pl
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@@ -37,6 +37,13 @@ my $base64url_out_nl = $base64url_out;
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$base64url_out_nl =~ s/(..)/\1\n/g; # add newline every two characters
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+# Bug 49741:
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+# The input is 'abc' in base64, in an 8K buffer (larger than 1024*5,
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+# the buffer size which caused the bug).
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+my $base64_bug49741_in = "YWJj" x 2000 ;
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+my $base64_bug49741_out = "abc" x 2000 ;
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+
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+
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my $base32_in = "\xfd\xd8\x07\xd1\xa5";
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my $base32_out = "7XMAPUNF";
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my $x = $base32_out;
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@@ -111,6 +118,8 @@ my @Tests =
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['b64u_7', '--base64url -d', {IN=>$base64_out},
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{EXIT=>1}, {ERR=>"$prog: invalid input\n"}],
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+ ['b64_bug49741', '--base64 -d', {IN=>$base64_bug49741_in},
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+ {OUT=>$base64_bug49741_out}],
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--
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2.42.0.windows.2
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