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From 42d359350510506b87101cf77202fefcbfc790cb 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.
Upstream-Status: Backport
CVE: CVE-2021-33574 patch#1
Signed-off-by: Armin Kuster <akuster@mvista.com>
---
NEWS | 4 ++++
sysdeps/unix/sysv/linux/mq_notify.c | 15 ++++++++++-----
2 files changed, 14 insertions(+), 5 deletions(-)
Index: git/NEWS
===================================================================
--- git.orig/NEWS
+++ git/NEWS
@@ -7,6 +7,10 @@ using `glibc' in the "product" field.
Version 2.31.1
+ 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:
[19519] iconv(1) with -c option hangs on illegal multi-byte sequences
(CVE-2016-10228)
Index: git/sysdeps/unix/sysv/linux/mq_notify.c
===================================================================
--- git.orig/sysdeps/unix/sysv/linux/mq_notify.c
+++ git/sysdeps/unix/sysv/linux/mq_notify.c
@@ -135,8 +135,11 @@ helper_thread (void *arg)
(void) __pthread_barrier_wait (¬ify_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;
}
@@ -257,8 +260,7 @@ mq_notify (mqd_t mqdes, const struct sig
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. */
@@ -272,7 +274,10 @@ mq_notify (mqd_t mqdes, const struct sig
/* 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;
}
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