Fix CVE-2026-58013: buffer over-read in GIOChannel with long terminators
Backport upstream fix for CVE-2026-58013, which addresses a
buffer over-read in GIOChannel when using multi-byte line
terminators. The memcmp() call could read past the end of
the internal GString buffer when the line extends to the
buffer boundary. The patch adds a length check before the
memcmp() and includes a new unit test. The test was adapted
for GLib 2.68 by replacing unavailable C99/GLib 2.70
constructs (uint8_t, g_steal_fd) with their GLib 2.68
equivalents.
CVE: CVE-2026-58013
Upstream patches:
- 9f557746c5.patch
Resolves: RHEL-212237
This commit was backported by Ymir, a Red Hat Enterprise Linux software maintenance AI agent.
Assisted-by: Ymir
This commit is contained in:
RHEL Packaging Agent
parent
02c48c2acb
commit
3c65c9e35d
170
CVE-2026-58013.patch
Normal file
170
CVE-2026-58013.patch
Normal file
@ -0,0 +1,170 @@
|
||||
From 89f27b020f0e61a66c9308a0e67846e155c110ba Mon Sep 17 00:00:00 2001
|
||||
From: Philip Withnall <pwithnall@gnome.org>
|
||||
Date: Tue, 28 Apr 2026 16:45:14 +0100
|
||||
Subject: [PATCH 1/2] giochannel: Fix memcmp() off the end of the buffer with
|
||||
long terminators
|
||||
MIME-Version: 1.0
|
||||
Content-Type: text/plain; charset=UTF-8
|
||||
Content-Transfer-Encoding: 8bit
|
||||
|
||||
If the line terminator is longer than a single byte, and the current
|
||||
line extends to the end of the buffer, and the buffer (which is a
|
||||
`GString`) is near a power of two in length (as that’s how `GString`s
|
||||
are allocated) it’s possible for the `memcmp()` which checks the
|
||||
terminator to read off the end of the string buffer.
|
||||
|
||||
Fix that by checking the terminator length against the last character
|
||||
before calling `memcmp()`. Add a unit test.
|
||||
|
||||
Spotted by linhlhq as #YWH-PGM9867-199. The fix is theirs (validated by
|
||||
me), and the unit test is adapted from their proof of concept.
|
||||
|
||||
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
|
||||
Fixes: #3925
|
||||
---
|
||||
glib/giochannel.c | 3 ++-
|
||||
glib/tests/io-channel.c | 60 +++++++++++++++++++++++++++++++++++++++++
|
||||
2 files changed, 62 insertions(+), 1 deletion(-)
|
||||
|
||||
diff --git a/glib/giochannel.c b/glib/giochannel.c
|
||||
index e93c4b458..66b68e645 100644
|
||||
--- a/glib/giochannel.c
|
||||
+++ b/glib/giochannel.c
|
||||
@@ -1830,7 +1830,8 @@ read_again:
|
||||
{
|
||||
if (channel->line_term)
|
||||
{
|
||||
- if (memcmp (channel->line_term, nextchar, line_term_len) == 0)
|
||||
+ if ((size_t) (lastchar - nextchar) >= line_term_len &&
|
||||
+ memcmp (channel->line_term, nextchar, line_term_len) == 0)
|
||||
{
|
||||
line_length = nextchar - use_buf->str;
|
||||
got_term_len = line_term_len;
|
||||
diff --git a/glib/tests/io-channel.c b/glib/tests/io-channel.c
|
||||
index 4a1b10876..c619fb00f 100644
|
||||
--- a/glib/tests/io-channel.c
|
||||
+++ b/glib/tests/io-channel.c
|
||||
@@ -69,6 +69,65 @@ test_read_line_embedded_nuls (void)
|
||||
g_free (filename);
|
||||
}
|
||||
|
||||
+static void
|
||||
+test_read_line_long_terminator (void)
|
||||
+{
|
||||
+ uint8_t *test_data = NULL;
|
||||
+ size_t test_data_len = 0;
|
||||
+ int fd;
|
||||
+ char *filename = NULL;
|
||||
+ GIOChannel *channel = NULL;
|
||||
+ GError *local_error = NULL;
|
||||
+ char *line = NULL;
|
||||
+ size_t line_length, terminator_pos;
|
||||
+ const char *line_term;
|
||||
+ int line_term_length;
|
||||
+ GIOStatus status;
|
||||
+
|
||||
+ g_test_summary ("Test that reading a line when using a long terminator doesn’t over-read the buffer.");
|
||||
+ g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/work_items/3925");
|
||||
+
|
||||
+ /* Write out a temporary file containing 2047 bytes. This is enough to make it
|
||||
+ * near the length of the GString buffer when read back in. */
|
||||
+ fd = g_file_open_tmp ("glib-test-io-channel-XXXXXX", &filename, &local_error);
|
||||
+ g_assert_no_error (local_error);
|
||||
+ g_close (g_steal_fd (&fd), NULL);
|
||||
+
|
||||
+ test_data_len = 2047;
|
||||
+ test_data = g_malloc (test_data_len);
|
||||
+ memset (test_data, 'M', test_data_len);
|
||||
+ g_file_set_contents (filename, (const gchar *) test_data, test_data_len, &local_error);
|
||||
+ g_assert_no_error (local_error);
|
||||
+
|
||||
+ /* Create the channel. */
|
||||
+ channel = g_io_channel_new_file (filename, "r", &local_error);
|
||||
+ g_assert_no_error (local_error);
|
||||
+
|
||||
+ /* Use a long line terminator so it could potentially over-read the end of the buffer. */
|
||||
+ g_io_channel_set_line_term (channel, "DEADBEEF", 8);
|
||||
+
|
||||
+ line_term = g_io_channel_get_line_term (channel, &line_term_length);
|
||||
+ g_assert_cmpstr (line_term, ==, "DEADBEEF");
|
||||
+ g_assert_cmpint (line_term_length, ==, 8);
|
||||
+
|
||||
+ g_io_channel_set_encoding (channel, "UTF-8", &local_error);
|
||||
+ g_assert_no_error (local_error);
|
||||
+
|
||||
+ status = g_io_channel_read_line (channel, &line, &line_length,
|
||||
+ &terminator_pos, &local_error);
|
||||
+ g_assert_no_error (local_error);
|
||||
+ g_assert_cmpint (status, ==, G_IO_STATUS_NORMAL);
|
||||
+ g_assert_cmpuint (line_length, ==, 2047);
|
||||
+ g_assert_cmpuint (terminator_pos, ==, 2047);
|
||||
+ g_assert_cmpmem (line, line_length, test_data, test_data_len);
|
||||
+
|
||||
+ g_free (line);
|
||||
+ g_io_channel_unref (channel);
|
||||
+ g_free (test_data);
|
||||
+ g_unlink (filename);
|
||||
+ g_free (filename);
|
||||
+}
|
||||
+
|
||||
int
|
||||
main (int argc,
|
||||
char *argv[])
|
||||
@@ -76,6 +135,7 @@ main (int argc,
|
||||
g_test_init (&argc, &argv, NULL);
|
||||
|
||||
g_test_add_func ("/io-channel/read-line/embedded-nuls", test_read_line_embedded_nuls);
|
||||
+ g_test_add_func ("/io-channel/read-line/long-terminator", test_read_line_long_terminator);
|
||||
|
||||
return g_test_run ();
|
||||
}
|
||||
|
||||
From 94b3e1b6d1380c8f78e1e869b5cb46b2fbfe6689 Mon Sep 17 00:00:00 2001
|
||||
From: RHEL Packaging Agent <redhat-ymir-agent@redhat.com>
|
||||
Date: Wed, 19 Aug 2026 15:07:16 +0000
|
||||
Subject: [PATCH 2/2] Adapt test for GLib 2.68: replace uint8_t with guint8 and
|
||||
g_steal_fd with inline equivalent
|
||||
|
||||
---
|
||||
glib/tests/io-channel.c | 19 ++++++++++---------
|
||||
1 file changed, 10 insertions(+), 9 deletions(-)
|
||||
|
||||
diff --git a/glib/tests/io-channel.c b/glib/tests/io-channel.c
|
||||
index c619fb00f..afcea93f0 100644
|
||||
--- a/glib/tests/io-channel.c
|
||||
+++ b/glib/tests/io-channel.c
|
||||
@@ -72,16 +72,16 @@ test_read_line_embedded_nuls (void)
|
||||
static void
|
||||
test_read_line_long_terminator (void)
|
||||
{
|
||||
- uint8_t *test_data = NULL;
|
||||
- size_t test_data_len = 0;
|
||||
- int fd;
|
||||
- char *filename = NULL;
|
||||
+ guint8 *test_data = NULL;
|
||||
+ gsize test_data_len = 0;
|
||||
+ gint fd;
|
||||
+ gchar *filename = NULL;
|
||||
GIOChannel *channel = NULL;
|
||||
GError *local_error = NULL;
|
||||
- char *line = NULL;
|
||||
- size_t line_length, terminator_pos;
|
||||
- const char *line_term;
|
||||
- int line_term_length;
|
||||
+ gchar *line = NULL;
|
||||
+ gsize line_length, terminator_pos;
|
||||
+ const gchar *line_term;
|
||||
+ gint line_term_length;
|
||||
GIOStatus status;
|
||||
|
||||
g_test_summary ("Test that reading a line when using a long terminator doesn’t over-read the buffer.");
|
||||
@@ -91,7 +91,8 @@ test_read_line_long_terminator (void)
|
||||
* near the length of the GString buffer when read back in. */
|
||||
fd = g_file_open_tmp ("glib-test-io-channel-XXXXXX", &filename, &local_error);
|
||||
g_assert_no_error (local_error);
|
||||
- g_close (g_steal_fd (&fd), NULL);
|
||||
+ g_close (fd, NULL);
|
||||
+ fd = -1;
|
||||
|
||||
test_data_len = 2047;
|
||||
test_data = g_malloc (test_data_len);
|
||||
@ -1,6 +1,6 @@
|
||||
Name: glib2
|
||||
Version: 2.68.4
|
||||
Release: 24%{?dist}
|
||||
Release: 25%{?dist}
|
||||
Summary: A library of handy utility functions
|
||||
|
||||
License: LGPLv2+
|
||||
@ -104,6 +104,9 @@ Patch: CVE-2026-58012.patch
|
||||
# https://gitlab.gnome.org/GNOME/glib/-/commit/aa1cb87d56111ef989811e824f0ac77484cc997f
|
||||
Patch: CVE-2026-58010.patch
|
||||
|
||||
# https://gitlab.gnome.org/GNOME/glib/-/commit/9f557746c52ae2a62fd5929f532b77024a18abe2
|
||||
Patch: CVE-2026-58013.patch
|
||||
|
||||
BuildRequires: chrpath
|
||||
BuildRequires: gcc
|
||||
BuildRequires: gcc-c++
|
||||
@ -325,6 +328,10 @@ glib-compile-schemas %{_datadir}/glib-2.0/schemas &> /dev/null || :
|
||||
%{_datadir}/installed-tests
|
||||
|
||||
%changelog
|
||||
* Wed Aug 19 2026 RHEL Packaging Agent <redhat-ymir-agent@redhat.com> - 2.68.4-25
|
||||
- Fix CVE-2026-58013: buffer over-read in GIOChannel with long terminators
|
||||
Resolves: RHEL-212237
|
||||
|
||||
* Wed Aug 19 2026 RHEL Packaging Agent <redhat-ymir-agent@redhat.com> - 2.68.4-24
|
||||
- Fix CVE-2026-58010: off-by-one error in GVariant tuple normal form checking
|
||||
Resolves: RHEL-212171
|
||||
|
||||
Loading…
Reference in New Issue
Block a user