high CVSS 7.1

CVE-2024-36027·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: do not flag ZEROOUT on non-dirty extent buffer Btrfs clears the content of an extent buffer marked as EXTENT_BUFFER_ZONED_ZEROOUT before the bio submission. This mechanism is introduced to prevent a write hole of an extent buffer, which is once allocated, marked dirty, but turns out unnecessary and cleaned up within one transaction operation. Currently, btrfs_clear_buffer_dirty() marks the extent buffer as EXTENT_BUFFER_ZONED_ZEROOUT, and skips the entry function. If this call happens while the buffer is under IO (with the WRITEBACK flag set, without the DIRTY flag), we can add the ZEROOUT flag and clear the buffer's content just before a bio submission. As a result: 1) it can lead to adding faulty delayed reference item which leads to a FS corrupted (EUCLEAN) error, and 2) it writes out cleared tree node on disk The former issue is previously discussed in [1]. The corruption happens when it runs a delayed reference update. So, on-disk data is safe. [1] https://lore.kernel.org/linux-btrfs/3f4f2a0ff1a6c818050434288925bdcf3cd719e5.1709124777.git.naohiro.aota@wdc.com/ The latter one can reach on-disk data. But, as that node is already processed by btrfs_clear_buffer_dirty(), that will be invalidated in the next transaction commit anyway. So, the chance of hitting the corruption is relatively small. Anyway, we should skip flagging ZEROOUT on a non-DIRTY extent buffer, to keep the content under IO intact.

Severity
high
Software
Kernel
Fixed in
6.8.8
Published
2024-05-30

Affected versions

From: 6.8

Until: 6.8.8

Fixed in: 6.8.8

How to fix this CVE

Update your Linux kernel to version 6.8.8 or later to resolve this btrfs zoned storage vulnerability. The fix prevents incorrect ZEROOUT flagging on extent buffers that are not dirty, which could lead to filesystem corruption or corrupted tree nodes being written to disk. Systems using btrfs on zoned block devices should prioritize this update.

sudo dnf update kernel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your installed kernel version with `uname -r`. If the version is between 6.8 and 6.8.7 (inclusive), your system is vulnerable.
  2. Step 2: Verify if your system uses btrfs filesystem with `df -t btrfs`. If btrfs is present and mounted, the vulnerability is potentially exploitable.
  3. Step 3: Check for zoned block device support with `cat /sys/block/*/queue/zoned`. If any device shows 'host-managed' or 'host-aware', the system is using zoned storage.
  4. Step 4: After updating, confirm the new kernel version with `uname -r`. The version should be 6.8.8 or higher, and reboot if necessary with `sudo reboot`.

FAQ

What is CVE-2024-36027?

This vulnerability affects the Linux kernel's btrfs filesystem when operating with zoned block devices. An incorrect buffer state check allows the kernel to improperly flag extent buffers for zeroing operations even when they are actively being written to disk, potentially causing filesystem corruption or data inconsistency.

Is CVE-2024-36027 being actively exploited?

No, this vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and has no public exploits available. However, it can still cause unintended data corruption on affected systems.

What versions of Kernel are affected by CVE-2024-36027?

Linux kernel versions 6.8 through 6.8.7 are vulnerable. The fix is included in kernel 6.8.8 and all subsequent releases.

How do I check if my server is vulnerable to CVE-2024-36027?

Run `uname -r` to check your kernel version. If it displays a version between 6.8 and 6.8.7, and `df -t btrfs` shows active btrfs mounts, your system is vulnerable.

Does Defensia detect CVE-2024-36027?

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-2024-36027 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-2024-36027. Free for 1 server.

Get started free