high CVSS 7.8

CVE-2021-47194·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: cfg80211: call cfg80211_stop_ap when switch from P2P_GO type If the userspace tools switch from NL80211_IFTYPE_P2P_GO to NL80211_IFTYPE_ADHOC via send_msg(NL80211_CMD_SET_INTERFACE), it does not call the cleanup cfg80211_stop_ap(), this leads to the initialization of in-use data. For example, this path re-init the sdata->assigned_chanctx_list while it is still an element of assigned_vifs list, and makes that linked list corrupt.

Severity
high
Software
Kernel
Fixed in
5.15.5
Published
2024-04-10

Affected versions

From: 5.11.0

Until: 5.15.5

Fixed in: 5.15.5

How to fix this CVE

Update your Linux kernel to version 5.15.5 or later to patch the P2P_GO interface mode switching vulnerability. This fix ensures that the cfg80211_stop_ap() cleanup function is properly invoked when transitioning from P2P_GO to ADHOC mode, preventing linked list corruption and data structure reinitialization issues. Reboot your system after applying the kernel update to activate the fix.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Check kernel version: uname -r — verify the version is 5.15.5 or later
  2. Identify 802.11 wireless devices: ip link show type wlan — confirm if WiFi/P2P devices are present on the system
  3. Search system logs for P2P_GO mode transitions: grep -i 'P2P_GO\|NL80211_CMD_SET_INTERFACE' /var/log/kernel.log /var/log/syslog 2>/dev/null — look for interface type change events
  4. Verify patch installation: grep -i 'cfg80211_stop_ap' /proc/config.gz 2>/dev/null || zcat /boot/config-$(uname -r).gz | grep -i cfg80211 — confirm the patched code is present

FAQ

What is CVE-2021-47194?

CVE-2021-47194 is a kernel vulnerability in the cfg80211 wireless configuration module where switching a WiFi interface from P2P_GO (P2P Group Owner) mode to ADHOC mode fails to execute the required cleanup routine, resulting in memory corruption and linked list corruption in kernel data structures.

Is CVE-2021-47194 being actively exploited?

No, CVE-2021-47194 is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available, though the vulnerability requires local access to trigger.

What versions of Kernel are affected by CVE-2021-47194?

Linux kernel versions 5.11.0 through 5.15.4 are affected; kernel 5.15.5 and later versions contain the fix.

How do I check if my server is vulnerable to CVE-2021-47194?

Run 'uname -r' and compare your kernel version against the vulnerable range (5.11.0–5.15.4); if your version falls within this range and you have WiFi hardware capable of P2P_GO mode, your system is vulnerable.

Does Defensia detect CVE-2021-47194?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2021-47194 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2024-42256CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: cifs: Fix server re-repick on subrequest retry When a subrequest is marked for needing retry, netfs will call cifs_prepare_write() which will make cifs repick the server for the op before renegotiating credits; it then calls cifs_issue_write() which invokes smb2_async_writev() - which re-repicks the server. If a different server is then selected, this causes the increment of server->in_flight to happen against one record and the decrement to happen against another, leading to misaccounting. Fix this by just removing the repick code in smb2_async_writev(). As this is only called from netfslib-driven code, cifs_prepare_write() should always have been called first, and so server should never be NULL and the preparatory step is repeated in the event that we do a retry. The problem manifests as a warning looking something like: WARNING: CPU: 4 PID: 72896 at fs/smb/client/smb2ops.c:97 smb2_add_credits+0x3f0/0x9e0 [cifs] ... RIP: 0010:smb2_add_credits+0x3f0/0x9e0 [cifs] ... smb2_writev_callback+0x334/0x560 [cifs] cifs_demultiplex_thread+0x77a/0x11b0 [cifs] kthread+0x187/0x1d0 ret_from_fork+0x34/0x60 ret_from_fork_asm+0x1a/0x30 Which may be triggered by a number of different xfstests running against an Azure server in multichannel mode. generic/249 seems the most repeatable, but generic/215, generic/249 and generic/308 may also show it.
CVE-2024-38541CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: of: module: add buffer overflow check in of_modalias() In of_modalias(), if the buffer happens to be too small even for the 1st snprintf() call, the len parameter will become negative and str parameter (if not NULL initially) will point beyond the buffer's end. Add the buffer overflow check after the 1st snprintf() call and fix such check after the strlen() call (accounting for the terminating NUL char).
CVE-2021-47548CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ethernet: hisilicon: hns: hns_dsaf_misc: fix a possible array overflow in hns_dsaf_ge_srst_by_port() The if statement: if (port >= DSAF_GE_NUM) return; limits the value of port less than DSAF_GE_NUM (i.e., 8). However, if the value of port is 6 or 7, an array overflow could occur: port_rst_off = dsaf_dev->mac_cb[port]->port_rst_off; because the length of dsaf_dev->mac_cb is DSAF_MAX_PORT_NUM (i.e., 6). To fix this possible array overflow, we first check port and if it is greater than or equal to DSAF_MAX_PORT_NUM, the function returns.
CVE-2024-38612CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: fix invalid unregister error path The error path of seg6_init() is wrong in case CONFIG_IPV6_SEG6_LWTUNNEL is not defined. In that case if seg6_hmac_init() fails, the genl_unregister_family() isn't called. This issue exist since commit 46738b1317e1 ("ipv6: sr: add option to control lwtunnel support"), and commit 5559cea2d5aa ("ipv6: sr: fix possible use-after-free and null-ptr-deref") replaced unregister_pernet_subsys() with genl_unregister_family() in this error path.
CVE-2022-48716CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ASoC: codecs: wcd938x: fix incorrect used of portid Mixer controls have the channel id in mixer->reg, which is not same as port id. port id should be derived from chan_info array. So fix this. Without this, its possible that we could corrupt struct wcd938x_sdw_priv by accessing port_map array out of range with channel id instead of port id.

References

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