high CVSS 7.1

CVE-2024-50278·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: dm cache: fix potential out-of-bounds access on the first resume Out-of-bounds access occurs if the fast device is expanded unexpectedly before the first-time resume of the cache table. This happens because expanding the fast device requires reloading the cache table for cache_create to allocate new in-core data structures that fit the new size, and the check in cache_preresume is not performed during the first resume, leading to the issue. Reproduce steps: 1. prepare component devices: dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 65536 linear /dev/sdc 8192" dmsetup create corig --table "0 524288 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct 2. load a cache table of 512 cache blocks, and deliberately expand the fast device before resuming the cache, making the in-core data structures inadequate. dmsetup create cache --notable dmsetup reload cache --table "0 524288 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" dmsetup reload cdata --table "0 131072 linear /dev/sdc 8192" dmsetup resume cdata dmsetup resume cache 3. suspend the cache to write out the in-core dirty bitset and hint array, leading to out-of-bounds access to the dirty bitset at offset 0x40: dmsetup suspend cache KASAN reports: BUG: KASAN: vmalloc-out-of-bounds in is_dirty_callback+0x2b/0x80 Read of size 8 at addr ffffc90000085040 by task dmsetup/90 (...snip...) The buggy address belongs to the virtual mapping at [ffffc90000085000, ffffc90000087000) created by: cache_ctr+0x176a/0x35f0 (...snip...) Memory state around the buggy address: ffffc90000084f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90000084f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >ffffc90000085000: 00 00 00 00 00 00 00 00 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffffc90000085080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90000085100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 Fix by checking the size change on the first resume.

Severity
high
Software
Kernel
Fixed in
6.11.8
Published
2024-11-19

Affected versions

From: 6.7

Until: 6.11.8

Fixed in: 6.11.8

How to fix this CVE

Update your Linux kernel to version 6.11.8 or later to patch a critical out-of-bounds memory access vulnerability in the dm-cache subsystem. This vulnerability is triggered when the fast storage device is expanded before the initial cache table resume, causing memory corruption during cache suspension. Immediate kernel patching is essential to prevent potential system crashes or data corruption.

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; verify it is 6.11.8 or later
  2. Check if dm-cache is in use by running 'dmsetup ls' and look for any cache targets in the output
  3. Search system logs for KASAN or memory access errors: 'sudo grep -i "kasan\|out-of-bounds\|vmalloc" /var/log/kern.log /var/log/syslog'
  4. Verify the fix by confirming the kernel includes commit 036dd6e3d2638103e0092864577ea1d091466b86 using 'git log --oneline | grep 036dd6e'

FAQ

What is CVE-2024-50278?

CVE-2024-50278 is a kernel memory safety bug in the device mapper cache subsystem where expanding a fast device before the initial cache resume leads to out-of-bounds memory access, potentially causing system instability or data corruption.

Is CVE-2024-50278 being actively exploited?

No, CVE-2024-50278 is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available, though it remains a serious local privilege/crash vulnerability.

What versions of Kernel are affected by CVE-2024-50278?

Linux kernel versions 6.7 through 6.11.7 are vulnerable; the fix is included in kernel 6.11.8 and later.

How do I check if my server is vulnerable to CVE-2024-50278?

Run 'uname -r' and compare the version against 6.11.8; if your kernel is between 6.7 and 6.11.7 and dm-cache is loaded (check with 'lsmod | grep dm_cache'), your system is vulnerable.

Does Defensia detect CVE-2024-50278?

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-2024-50278 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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