67 lines
2.0 KiB
Diff
67 lines
2.0 KiB
Diff
From b3959fc691e606857a3c6e9b316ec34819972245 Mon Sep 17 00:00:00 2001
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From: Jim Meyering <meyering@redhat.com>
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Date: Sat, 28 Aug 2010 17:45:29 +0200
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Subject: [PATCH] tac: avoid double free
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* src/tac.c (main): Reading a line longer than 16KiB would cause
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tac to realloc its primary buffer. Then, just before exit, tac
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would mistakenly free the original (now free'd) buffer.
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This bug was introduced by commit be6c13e7, "maint: always free a
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buffer, to avoid even semblance of a leak".
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* tests/misc/tac (double-free): New test, to exercise this.
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Reported by Salvo Tomaselli in <http://bugs.debian.org/594666>.
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---
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src/tac.c | 6 ++++--
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tests/misc/tac | 6 ++++++
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2 files changed, 10 insertions(+), 2 deletions(-)
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diff --git a/src/tac.c b/src/tac.c
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index cec9736..859e006 100644
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--- a/src/tac.c
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+++ b/src/tac.c
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@@ -633,7 +633,6 @@ main (int argc, char **argv)
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if (! (read_size < half_buffer_size && half_buffer_size < G_buffer_size))
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xalloc_die ();
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G_buffer = xmalloc (G_buffer_size);
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- void *buf = G_buffer;
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if (sentinel_length)
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{
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strcpy (G_buffer, separator);
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@@ -666,6 +665,9 @@ main (int argc, char **argv)
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error (0, errno, "-");
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ok = false;
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}
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- free (buf);
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+
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+ size_t offset = sentinel_length ? sentinel_length : 1;
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+ free (G_buffer - offset);
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+
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exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
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}
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diff --git a/tests/misc/tac b/tests/misc/tac
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index 7631049..4130c00 100755
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--- a/tests/misc/tac
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+++ b/tests/misc/tac
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@@ -24,6 +24,9 @@ my $prog = 'tac';
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my $bad_dir = 'no/such/dir';
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+# This must be longer than 16KiB to trigger the double free in coreutils-8.5.
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+my $long_line = 'o' x (16 * 1024 + 1);
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+
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my @Tests =
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(
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['segfault', '-r', {IN=>"a\n"}, {IN=>"b\n"}, {OUT=>"a\nb\n"}],
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@@ -67,6 +70,9 @@ my @Tests =
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{ERR_SUBST => "s,`$bad_dir': .*,...,"},
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{ERR => "$prog: cannot create temporary file in ...\n"},
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{EXIT => 1}],
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+
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+ # coreutils-8.5's tac would double-free its primary buffer.
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+ ['double-free', {IN=>$long_line}, {OUT=>$long_line}],
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);
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@Tests = triple_test \@Tests;
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--
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1.7.2.2.510.g7180a
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