high CVSS 7.8

CVE-2022-48822·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: usb: f_fs: Fix use-after-free for epfile Consider a case where ffs_func_eps_disable is called from ffs_func_disable as part of composition switch and at the same time ffs_epfile_release get called from userspace. ffs_epfile_release will free up the read buffer and call ffs_data_closed which in turn destroys ffs->epfiles and mark it as NULL. While this was happening the driver has already initialized the local epfile in ffs_func_eps_disable which is now freed and waiting to acquire the spinlock. Once spinlock is acquired the driver proceeds with the stale value of epfile and tries to free the already freed read buffer causing use-after-free. Following is the illustration of the race: CPU1 CPU2 ffs_func_eps_disable epfiles (local copy) ffs_epfile_release ffs_data_closed if (last file closed) ffs_data_reset ffs_data_clear ffs_epfiles_destroy spin_lock dereference epfiles Fix this races by taking epfiles local copy & assigning it under spinlock and if epfiles(local) is null then update it in ffs->epfiles then finally destroy it. Extending the scope further from the race, protecting the ep related structures, and concurrent accesses.

Severity
high
Software
Kernel
Fixed in
5.16.10
Published
2024-07-16

Affected versions

From: 5.16

Until: 5.16.10

Fixed in: 5.16.10

How to fix this CVE

Update your Linux kernel to version 5.16.10 or later to patch a critical use-after-free vulnerability in the USB gadget function fs (f_fs) driver. This flaw occurs when concurrent operations between composition switching and file release cause stale epfile pointers to be dereferenced, leading to potential kernel memory corruption. Apply the kernel update immediately and reboot your system to enable the fix.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed kernel version: uname -r and verify it is 5.16.10 or later
  2. Confirm f_fs module is loaded: lsmod | grep f_fs (vulnerability only impacts systems with USB gadget mode enabled)
  3. Monitor dmesg logs for use-after-free warnings: dmesg | grep -i 'use-after-free\|UAF\|ffs_func_eps_disable' and check system logs at /var/log/kern.log for kernel crashes
  4. Verify patch was applied: grep -i 'ffs_func_eps_disable\|epfiles_destroy' /boot/config-$(uname -r) and confirm kernel build includes USB gadget function fs fixes

FAQ

What is CVE-2022-48822?

CVE-2022-48822 is a use-after-free vulnerability in the Linux kernel's USB gadget function fs (f_fs) driver that occurs when concurrent threads attempt to simultaneously disable endpoints and release file descriptors, causing freed memory to be accessed.

Is CVE-2022-48822 being actively exploited?

No, CVE-2022-48822 is not listed in CISA's Known Exploited Vulnerabilities catalog and no public exploits are currently available, though the vulnerability poses a high local privilege escalation risk.

What versions of Kernel are affected by CVE-2022-48822?

Linux kernel versions 5.16 through 5.16.9 are affected; the vulnerability is resolved in kernel 5.16.10 and later.

How do I check if my server is vulnerable to CVE-2022-48822?

Run 'uname -r' to check your kernel version; if it shows 5.16.0 through 5.16.9, your system is vulnerable. Also verify USB gadget mode is enabled with 'lsmod | grep f_fs'.

Does Defensia detect CVE-2022-48822?

Yes — Defensia's CVE advisory scanner compares installed kernel versions against the NVD database. If a vulnerable kernel (5.16.0-5.16.9) is detected on monitored systems, CVE-2022-48822 will appear in your dashboard with automated remediation steps and priority alerts.

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-2022-48822. Free for 1 server.

Get started free