CVE-2022-50459: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: iscsi: iscsi_tcp: Fix null-ptr-deref while calling getpeername() Fix a NULL pointer crash that occurs when we are freeing the socket at the same time we access it via sysfs. The problem is that: 1. iscsi_sw_tcp_conn_get_param() and iscsi_sw_tcp_host_get_param() take the frwd_lock and do sock_hold() then drop the frwd_lock. sock_hold() does a get on the "struct sock". 2. iscsi_sw_tcp_release_conn() does sockfd_put() which does the last put on the "struct socket" and that does __sock_release() which sets the sock->ops to NULL. 3. iscsi_sw_tcp_conn_get_param() and iscsi_sw_tcp_host_get_param() then call kernel_getpeername() which accesses the NULL sock->ops. Above we do a get on the "struct sock", but we needed a get on the "struct socket". Originally, we just held the frwd_lock the entire time but in commit bcf3a2953d36 ("scsi: iscsi: iscsi_tcp: Avoid holding spinlock while calling getpeername()") we switched to refcount based because the network layer changed and started taking a mutex in that path, so we could no longer hold the frwd_lock. Instead of trying to maintain multiple refcounts, this just has us use a mutex for accessing the socket in the interface code paths.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.8.14 — 5.9
linux	linux_kernel	5.9.1 — 5.10.150
linux	linux_kernel	5.11 — 5.15.75
linux	linux_kernel	5.16 — 5.19.17
linux	linux_kernel	6.0 — 6.0.3
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/0a0b861fce2657ba08ec356a74346b37ca4b2008 https://git.kernel.org/stable/c/57569c37f0add1b6489e1a1563c71519daf732cf https://git.kernel.org/stable/c/884a788f065578bb640382279a83d1df433b13e6 https://git.kernel.org/stable/c/897dbbc57d71e8a34ec1af8e573a142de457da38 https://git.kernel.org/stable/c/a26b0658751bb0a3b28386fca715333b104d32a2

Frequently Asked Questions

What is CVE-2022-50459? +

In the Linux kernel, the following vulnerability has been resolved: scsi: iscsi: iscsi_tcp: Fix null-ptr-deref while calling getpeername() Fix a NULL pointer crash that occurs when we are freeing the socket at the same time we access it via sysfs. The problem is that: 1. iscsi_sw_tcp_conn_get_param() and iscsi_sw_tcp_host_get_param() take the frwd_lock and do sock_hold() then drop the frwd_lock. sock_hold() does a get on the "struct sock". 2. iscsi_sw_tcp_release_conn() does sockfd_put() which does the last put on the "struct socket" and that does __sock_release() which sets the sock->ops to NULL. 3. iscsi_sw_tcp_conn_get_param() and iscsi_sw_tcp_host_get_param() then call kernel_getpeername() which accesses the NULL sock->ops. Above we do a get on the "struct sock", but we needed a get on the "struct socket". Originally, we just held the frwd_lock the entire time but in commit bcf3a2953d36 ("scsi: iscsi: iscsi_tcp: Avoid holding spinlock while calling getpeername()") we switched to refcount based because the network layer changed and started taking a mutex in that path, so we could no longer hold the frwd_lock. Instead of trying to maintain multiple refcounts, this just has us use a mutex for accessing the socket in the interface code paths. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2022-50459? +

CVE-2022-50459 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2022-50459? +

CVE-2022-50459 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2022-50459? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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