CVE-2019-19813 - Use After Free

Severity

55%

Complexity

18%

Confidentiality

60%

In the Linux kernel 5.0.21, mounting a crafted btrfs filesystem image, performing some operations, and then making a syncfs system call can lead to a use-after-free in __mutex_lock in kernel/locking/mutex.c. This is related to mutex_can_spin_on_owner in kernel/locking/mutex.c, __btrfs_qgroup_free_meta in fs/btrfs/qgroup.c, and btrfs_insert_delayed_items in fs/btrfs/delayed-inode.c.

In the Linux kernel 5.0.21, mounting a crafted btrfs filesystem image, performing some operations, and then making a syncfs system call can lead to a use-after-free in __mutex_lock in kernel/locking/mutex.c. This is related to mutex_can_spin_on_owner in kernel/locking/mutex.c, __btrfs_qgroup_free_meta in fs/btrfs/qgroup.c, and btrfs_insert_delayed_items in fs/btrfs/delayed-inode.c.

CVSS 3.1 Base Score 5.5. CVSS Attack Vector: local. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H).

CVSS 2.0 Base Score 7.1. CVSS Attack Vector: network. CVSS Attack Complexity: medium. CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:N/A:C).

Demo Examples

Use After Free

CWE-416

The following example demonstrates the weakness.


               
}
free(buf3R2);

Use After Free

CWE-416

The following code illustrates a use after free error:


               
}
free(ptr);
logError("operation aborted before commit", ptr);

When an error occurs, the pointer is immediately freed. However, this pointer is later incorrectly used in the logError function.

Overview

First reported 5 years ago

2019-12-17 06:15:00

Last updated 4 years ago

2020-04-03 13:00:00

Affected Software

Linux Kernel 5.0.21

5.0.21

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