high CVSS 7.8

CVE-2021-47063·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: drm: bridge/panel: Cleanup connector on bridge detach If we don't call drm_connector_cleanup() manually in panel_bridge_detach(), the connector will be cleaned up with the other DRM objects in the call to drm_mode_config_cleanup(). However, since our drm_connector is devm-allocated, by the time drm_mode_config_cleanup() will be called, our connector will be long gone. Therefore, the connector must be cleaned up when the bridge is detached to avoid use-after-free conditions. v2: Cleanup connector only if it was created v3: Add FIXME v4: (Use connector->dev) directly in if() block

Severity
high
Software
Kernel
Fixed in
5.12.4
Published
2024-02-29

Affected versions

From: 5.12

Until: 5.12.4

Fixed in: 5.12.4

How to fix this CVE

Update your Linux kernel to version 5.12.4 or later to resolve a use-after-free vulnerability in the DRM bridge/panel connector cleanup logic. This vulnerability can occur when a display bridge is detached, leaving dangling connector pointers that may be accessed during system shutdown or module unloading. Ensure your system is running a patched kernel version and reboot to activate the fix.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version with `uname -r` and verify if it falls within 5.12 to 5.12.3 range
  2. Step 2: Verify DRM/graphics subsystem is in use by checking `lsmod | grep drm` for loaded DRM modules
  3. Step 3: Search kernel logs for memory errors related to connectors: `sudo dmesg | grep -i 'use-after-free\|connector\|drm.*error'`
  4. Step 4: After patching, confirm kernel version is 5.12.4 or higher with `uname -r` and reboot if needed

FAQ

What is CVE-2021-47063?

CVE-2021-47063 is a use-after-free vulnerability in the Linux kernel's DRM (Direct Rendering Manager) bridge/panel subsystem. When a display bridge is detached, the connector object may be cleaned up prematurely, but references to it persist in the device model, leading to potential memory corruption or denial of service.

Is CVE-2021-47063 being actively exploited?

No, CVE-2021-47063 is not listed on CISA's Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available. However, the vulnerability can still be triggered through normal system operations involving graphics driver detachment.

What versions of Kernel are affected by CVE-2021-47063?

Linux kernel versions 5.12 through 5.12.3 are vulnerable. Kernel 5.12.4 and later versions include the fix.

How do I check if my server is vulnerable to CVE-2021-47063?

Run `uname -r` to check your kernel version. If the output shows 5.12.0, 5.12.1, 5.12.2, or 5.12.3, your system is vulnerable and requires immediate patching.

Does Defensia detect CVE-2021-47063?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel package is installed on a monitored server within the vulnerable version range, CVE-2021-47063 will appear in your dashboard with remediation steps.

Related Kernel CVEs

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CVE-2024-36031CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: keys: Fix overwrite of key expiration on instantiation The expiry time of a key is unconditionally overwritten during instantiation, defaulting to turn it permanent. This causes a problem for DNS resolution as the expiration set by user-space is overwritten to TIME64_MAX, disabling further DNS updates. Fix this by restoring the condition that key_set_expiry is only called when the pre-parser sets a specific expiry.
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-2024-38623CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: Use variable length array instead of fixed size Should fix smatch warning: ntfs_set_label() error: __builtin_memcpy() 'uni->name' too small (20 vs 256)
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.

References

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