high CVSS 7.1

CVE-2021-47604·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: vduse: check that offset is within bounds in get_config() This condition checks "len" but it does not check "offset" and that could result in an out of bounds read if "offset > dev->config_size". The problem is that since both variables are unsigned the "dev->config_size - offset" subtraction would result in a very high unsigned value. I think these checks might not be necessary because "len" and "offset" are supposed to already have been validated using the vhost_vdpa_config_validate() function. But I do not know the code perfectly, and I like to be safe.

Severity
high
Software
Kernel
Fixed in
5.15.11
Published
2024-06-19

Affected versions

From: 5.15

Until: 5.15.11

Fixed in: 5.15.11

How to fix this CVE

Update your Linux kernel to version 5.15.11 or later to address a bounds-checking vulnerability in the vduse subsystem's get_config() function. This vulnerability could allow local attackers with limited privileges to read sensitive kernel memory by exploiting improper offset validation. Apply the patch immediately to systems running kernel versions 5.15.0 through 5.15.10.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'uname -r' to check your current kernel version and confirm if it falls within the vulnerable range (5.15.0-5.15.10)
  2. Verify vduse module is loaded by running 'lsmod | grep vduse'; if present, your system could be affected
  3. Check kernel logs for vduse-related errors using 'dmesg | grep -i vduse' to identify any abnormal memory access attempts
  4. After patching, confirm the new kernel version with 'uname -r' and verify it is 5.15.11 or later

FAQ

What is CVE-2021-47604?

This vulnerability exists in the Linux kernel's vduse (vhost-user device) subsystem where the get_config() function fails to properly validate the offset parameter before performing a read operation, potentially allowing out-of-bounds memory access by unprivileged local users.

Is CVE-2021-47604 being actively exploited?

No, this CVE is not listed in CISA's Known Exploited Vulnerabilities catalog and no public exploits are currently available. However, the vulnerability is technically sound and should be patched promptly.

What versions of Kernel are affected by CVE-2021-47604?

Linux kernel versions 5.15.0 through 5.15.10 are affected. The vulnerability was fixed in version 5.15.11.

How do I check if my server is vulnerable to CVE-2021-47604?

Execute 'uname -r' to display your kernel version. If the output shows a version between 5.15.0 and 5.15.10, your system requires the patch. Additionally, check if the vduse module is in use with 'lsmod | grep vduse'.

Does Defensia detect CVE-2021-47604?

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-2021-47604 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

Track CVEs across your fleet automatically

Defensia scans your Linux servers and tells you exactly which ones are running vulnerable versions — including CVE-2021-47604. Free for 1 server.

Get started free