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glibc: Fix CVE-2021-33574 and follow-up issue

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The mq_notify function has a potential use-after-free issue when using a
notification type of SIGEV_THREAD and a thread attribute with a non-default
affinity mask.

The fix for this introduced a NULL pointer dereference.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>
This commit is contained in:
Michael Tremer
2021-08-19 12:07:06 +00:00
committed by Arne Fitzenreiter
parent 2664c94463
commit b9a4368adb
3 changed files with 118 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
src/patches/glibc-2.33-librt-fix-null-pointer-dereference-bug-28213.patch Normal file
View File

@@ -0,0 +1,40 @@
From 27a78fd712c06748737dfa9638fab96ea362fca9 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npv1310@gmail.com>
Date: Mon, 9 Aug 2021 20:17:34 +0530
Subject: [PATCH] librt: fix NULL pointer dereference (bug 28213)
Helper thread frees copied attribute on NOTIFY_REMOVED message
received from the OS kernel. Unfortunately, it fails to check whether
copied attribute actually exists (data.attr != NULL). This worked
earlier because free() checks passed pointer before actually
attempting to release corresponding memory. But
__pthread_attr_destroy assumes pointer is not NULL.
So passing NULL pointer to __pthread_attr_destroy will result in
segmentation fault. This scenario is possible if
notification->sigev_notify_attributes == NULL (which means default
thread attributes should be used).
Signed-off-by: Nikita Popov <npv1310@gmail.com>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
(cherry picked from commit b805aebd42364fe696e417808a700fdb9800c9e8)
---
sysdeps/unix/sysv/linux/mq_notify.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c
index 6f46d29d1d..1714e1cc5f 100644
--- a/sysdeps/unix/sysv/linux/mq_notify.c
+++ b/sysdeps/unix/sysv/linux/mq_notify.c
@@ -132,7 +132,7 @@ helper_thread (void *arg)
to wait until it is done with it. */
(void) __pthread_barrier_wait (&notify_barrier);
}
- else if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_REMOVED)
+ else if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_REMOVED && data.attr != NULL)
{
/* The only state we keep is the copy of the thread attributes. */
pthread_attr_destroy (data.attr);
--
2.20.1

74
src/patches/glibc-2.33-use-__pthread_attr_copy-in-mq_notify-bug-27896.patch Normal file
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@@ -0,0 +1,74 @@
From 4b6be914bd3920500a67ef6ca1aa7d1c37e5e859 Mon Sep 17 00:00:00 2001
From: Andreas Schwab <schwab@linux-m68k.org>
Date: Thu, 27 May 2021 12:49:47 +0200
Subject: [PATCH] Use __pthread_attr_copy in mq_notify (bug 27896)
Make a deep copy of the pthread attribute object to remove a potential
use-after-free issue.
(cherry picked from commit 42d359350510506b87101cf77202fefcbfc790cb)
---
NEWS | 6 ++++++
sysdeps/unix/sysv/linux/mq_notify.c | 15 ++++++++++-----
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/NEWS b/NEWS
index 0c33a80af9..b9e570b4a4 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,12 @@ Major new features:
a dump of information related to IFUNC resolver operation and
glibc-hwcaps subdirectory selection.
+Security related changes:
+
+ CVE-2021-33574: The mq_notify function has a potential use-after-free
+ issue when using a notification type of SIGEV_THREAD and a thread
+ attribute with a non-default affinity mask.
+
The following bugs are resolved with this release:
[15271] dlfcn function failure after dlmopen terminates process
diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c
index cc575a0cdd..f7ddfe5a6c 100644
--- a/sysdeps/unix/sysv/linux/mq_notify.c
+++ b/sysdeps/unix/sysv/linux/mq_notify.c
@@ -133,8 +133,11 @@ helper_thread (void *arg)
(void) __pthread_barrier_wait (&notify_barrier);
}
else if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_REMOVED)
- /* The only state we keep is the copy of the thread attributes. */
- free (data.attr);
+ {
+ /* The only state we keep is the copy of the thread attributes. */
+ pthread_attr_destroy (data.attr);
+ free (data.attr);
+ }
}
return NULL;
}
@@ -255,8 +258,7 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)
if (data.attr == NULL)
return -1;
- memcpy (data.attr, notification->sigev_notify_attributes,
- sizeof (pthread_attr_t));
+ __pthread_attr_copy (data.attr, notification->sigev_notify_attributes);
}
/* Construct the new request. */
@@ -270,7 +272,10 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)
/* If it failed, free the allocated memory. */
if (__glibc_unlikely (retval != 0))
- free (data.attr);
+ {
+ pthread_attr_destroy (data.attr);
+ free (data.attr);
+ }
return retval;
}
--
2.20.1