CVE-2015-8374: Infoleak
An information leak vulnerability was found when truncating a file to a smaller size which consists of an inline extent that is compressed. The data between the new file size and the old file size were not discarded, wasting metadata space and allowing for the truncated data to be leaked and the data corruption/loss to occur. The number of bytes used by the inode were not correctly decremented, which gives wrong report for callers of the stat(2) syscall. It is possible for a caller of the clone ioctl to actually read the data that was truncated, allowing for a security breach without requiring root access to the system, using only standard filesystem operations.
Upstream patch (includes reproducing steps):
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0305cd5f7fca85dae392b9ba85b116896eb7c1c7
CVE request:
http://seclists.org/oss-sec/2015/q4/391
Other sources
fs/btrfs/inode.c in the Linux kernel before 4.3.3 mishandles compressed inline extents, which allows local users to obtain sensitive pre-truncation information from a file via a clone action.
— Launchpad
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the vulnerability ID for this vulnerability?
The vulnerability ID for this vulnerability is CVE-2015-8374.
What is the severity of CVE-2015-8374?
CVE-2015-8374 has a severity level of medium.
How does CVE-2015-8374 impact the Linux kernel?
CVE-2015-8374 allows local users to obtain sensitive pre-truncation information from a file via a clone action in the Linux kernel.
Which versions of Ubuntu are affected by CVE-2015-8374?
The following versions of Ubuntu are affected by CVE-2015-8374: 3.2.0-98.138, 3.13.0-77.121, 3.19.0-49.55, 4.2.0-27.32, and 4.4~.
Where can I find more information about CVE-2015-8374?
You can find more information about CVE-2015-8374 at the following references: [Reference 1](https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0305cd5f7fca85dae392b9ba85b116896eb7c1c7), [Reference 2](http://seclists.org/oss-sec/2015/q4/391), [Reference 3](https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1286262).