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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 [https://sourceware.org/git/?p=glibc.git;a=commit;h=42d359350510506b87101cf77202fefcbfc790cb]
CVE: CVE-2021-33574
Signed-off-by: Vinay Kumar <vinay.m.engg@gmail.com>
---
diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c
index cc575a0cdd8..6f46d29d1dc 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 (¬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;
}
@@ -255,8 +258,14 @@ 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));
+ int ret = __pthread_attr_copy (data.attr,
+ notification->sigev_notify_attributes);
+ if (ret != 0)
+ {
+ free (data.attr);
+ __set_errno (ret);
+ return -1;
+ }
}
/* Construct the new request. */
@@ -269,8 +278,11 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)
int retval = INLINE_SYSCALL (mq_notify, 2, mqdes, &se);
/* If it failed, free the allocated memory. */
- if (__glibc_unlikely (retval != 0))
- free (data.attr);
+ if (retval != 0 && data.attr != NULL)
+ {
+ pthread_attr_destroy (data.attr);
+ free (data.attr);
+ }
return retval;
}
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