high CVSS 7.8

CVE-2024-47727·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: x86/tdx: Fix "in-kernel MMIO" check TDX only supports kernel-initiated MMIO operations. The handle_mmio() function checks if the #VE exception occurred in the kernel and rejects the operation if it did not. However, userspace can deceive the kernel into performing MMIO on its behalf. For example, if userspace can point a syscall to an MMIO address, syscall does get_user() or put_user() on it, triggering MMIO #VE. The kernel will treat the #VE as in-kernel MMIO. Ensure that the target MMIO address is within the kernel before decoding instruction.

Severity
high
Software
Kernel
Fixed in
6.11.2
Published
2024-10-21

Affected versions

From: 6.11

Until: 6.11.2

Fixed in: 6.11.2

How to fix this CVE

Update the Linux kernel to version 6.11.2 or later to patch the TDX MMIO validation bypass vulnerability. This fix adds a critical check to ensure MMIO addresses originate from kernel space rather than userspace, preventing privilege escalation attacks. Systems running kernel versions 6.11 through 6.11.1 should prioritize this update immediately.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'uname -r' to check the currently running kernel version and verify it is 6.11.2 or later
  2. Verify TDX capability with 'grep -i tdx /proc/cpuinfo' to confirm if the system uses TDX features
  3. Check for MMIO-related #VE exceptions in kernel logs using 'sudo dmesg | grep -i mmio' or 'sudo journalctl | grep -i mmio'
  4. After patching, reboot and confirm the new kernel version with 'uname -r', then validate no MMIO validation errors appear in dmesg

FAQ

What is CVE-2024-47727?

CVE-2024-47727 is a vulnerability in the Linux kernel's TDX (Intel Trust Domain Extensions) implementation where insufficient validation of MMIO address origins allows unprivileged userspace processes to trick the kernel into performing memory-mapped I/O operations on their behalf, bypassing TDX security boundaries.

Is CVE-2024-47727 being actively exploited?

No, CVE-2024-47727 is not currently listed on CISA's Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available. However, the vulnerability carries high severity due to its potential for privilege escalation on TDX-enabled systems.

What versions of Kernel are affected by CVE-2024-47727?

Linux kernel versions 6.11.0, 6.11.1, and 6.11.2 (prior to the patch) are affected. The vulnerability is resolved in kernel 6.11.2 and later.

How do I check if my server is vulnerable to CVE-2024-47727?

Run 'uname -r' to get your kernel version. If it shows 6.11.0 or 6.11.1, you are vulnerable. You can also verify TDX enablement with 'dmesg | grep -i tdx' to confirm if your hardware supports the affected feature.

Does Defensia detect CVE-2024-47727?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2024-47727 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-2024-36031CVSS 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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