high CVSS 7.8

CVE-2024-49889·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ext4: avoid use-after-free in ext4_ext_show_leaf() In ext4_find_extent(), path may be freed by error or be reallocated, so using a previously saved *ppath may have been freed and thus may trigger use-after-free, as follows: ext4_split_extent path = *ppath; ext4_split_extent_at(ppath) path = ext4_find_extent(ppath) ext4_split_extent_at(ppath) // ext4_find_extent fails to free path // but zeroout succeeds ext4_ext_show_leaf(inode, path) eh = path[depth].p_hdr // path use-after-free !!! Similar to ext4_split_extent_at(), we use *ppath directly as an input to ext4_ext_show_leaf(). Fix a spelling error by the way. Same problem in ext4_ext_handle_unwritten_extents(). Since 'path' is only used in ext4_ext_show_leaf(), remove 'path' and use *ppath directly. This issue is triggered only when EXT_DEBUG is defined and therefore does not affect functionality.

Severity
high
Software
Kernel
Fixed in
6.11.3
Published
2024-10-21

Affected versions

From: 6.11

Until: 6.11.3

Fixed in: 6.11.3

How to fix this CVE

Update your Linux kernel to version 6.11.3 or later to resolve a use-after-free vulnerability in the ext4 extent handling code. This flaw can lead to memory corruption when the EXT_DEBUG kernel debugging option is enabled. Systems with standard kernel configurations are unlikely to be affected, but patching is recommended for defense-in-depth security posture.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'uname -r' to check your current kernel version; vulnerable versions are 6.11.0 through 6.11.2
  2. Verify if EXT_DEBUG is enabled by checking 'cat /boot/config-$(uname -r) | grep CONFIG_EXT_DEBUG' — if it returns 'CONFIG_EXT_DEBUG=y', the system is at risk
  3. Search system logs for kernel panics or memory corruption warnings with 'dmesg | grep -i 'use-after-free\|ext4\|memory'
  4. After patching, confirm the new kernel version is active by running 'uname -r' and verifying it matches 6.11.3 or later

FAQ

What is CVE-2024-49889?

CVE-2024-49889 is a use-after-free vulnerability in the Linux kernel's ext4 filesystem code that occurs when extent path structures are freed prematurely during split operations. This can cause memory corruption and kernel crashes when EXT_DEBUG is enabled.

Is CVE-2024-49889 being actively exploited?

No, this vulnerability is not currently being actively exploited in the wild, and no public exploit code is available. However, attackers with local kernel debugging capabilities could potentially craft an exploit.

What versions of Kernel are affected by CVE-2024-49889?

Linux kernel versions 6.11.0, 6.11.1, and 6.11.2 are vulnerable. Version 6.11.3 and all subsequent releases contain the fix.

How do I check if my server is vulnerable to CVE-2024-49889?

Run 'uname -r' to check your kernel version — if it shows 6.11.0 through 6.11.2, your system may be vulnerable. Additionally, run 'cat /boot/config-$(uname -r) | grep CONFIG_EXT_DEBUG' to determine if the debugging component is active.

Does Defensia detect CVE-2024-49889?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2024-49889 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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