high CVSS 7.8

CVE-2024-50151·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix OOBs when building SMB2_IOCTL request When using encryption, either enforced by the server or when using 'seal' mount option, the client will squash all compound request buffers down for encryption into a single iov in smb2_set_next_command(). SMB2_ioctl_init() allocates a small buffer (448 bytes) to hold the SMB2_IOCTL request in the first iov, and if the user passes an input buffer that is greater than 328 bytes, smb2_set_next_command() will end up writing off the end of @rqst->iov[0].iov_base as shown below: mount.cifs //srv/share /mnt -o ...,seal ln -s $(perl -e "print('a')for 1..1024") /mnt/link BUG: KASAN: slab-out-of-bounds in smb2_set_next_command.cold+0x1d6/0x24c [cifs] Write of size 4116 at addr ffff8881148fcab8 by task ln/859 CPU: 1 UID: 0 PID: 859 Comm: ln Not tainted 6.12.0-rc3 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x5d/0x80 ? smb2_set_next_command.cold+0x1d6/0x24c [cifs] print_report+0x156/0x4d9 ? smb2_set_next_command.cold+0x1d6/0x24c [cifs] ? __virt_addr_valid+0x145/0x310 ? __phys_addr+0x46/0x90 ? smb2_set_next_command.cold+0x1d6/0x24c [cifs] kasan_report+0xda/0x110 ? smb2_set_next_command.cold+0x1d6/0x24c [cifs] kasan_check_range+0x10f/0x1f0 __asan_memcpy+0x3c/0x60 smb2_set_next_command.cold+0x1d6/0x24c [cifs] smb2_compound_op+0x238c/0x3840 [cifs] ? kasan_save_track+0x14/0x30 ? kasan_save_free_info+0x3b/0x70 ? vfs_symlink+0x1a1/0x2c0 ? do_symlinkat+0x108/0x1c0 ? __pfx_smb2_compound_op+0x10/0x10 [cifs] ? kmem_cache_free+0x118/0x3e0 ? cifs_get_writable_path+0xeb/0x1a0 [cifs] smb2_get_reparse_inode+0x423/0x540 [cifs] ? __pfx_smb2_get_reparse_inode+0x10/0x10 [cifs] ? rcu_is_watching+0x20/0x50 ? __kmalloc_noprof+0x37c/0x480 ? smb2_create_reparse_symlink+0x257/0x490 [cifs] ? smb2_create_reparse_symlink+0x38f/0x490 [cifs] smb2_create_reparse_symlink+0x38f/0x490 [cifs] ? __pfx_smb2_create_reparse_symlink+0x10/0x10 [cifs] ? find_held_lock+0x8a/0xa0 ? hlock_class+0x32/0xb0 ? __build_path_from_dentry_optional_prefix+0x19d/0x2e0 [cifs] cifs_symlink+0x24f/0x960 [cifs] ? __pfx_make_vfsuid+0x10/0x10 ? __pfx_cifs_symlink+0x10/0x10 [cifs] ? make_vfsgid+0x6b/0xc0 ? generic_permission+0x96/0x2d0 vfs_symlink+0x1a1/0x2c0 do_symlinkat+0x108/0x1c0 ? __pfx_do_symlinkat+0x10/0x10 ? strncpy_from_user+0xaa/0x160 __x64_sys_symlinkat+0xb9/0xf0 do_syscall_64+0xbb/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f08d75c13bb

Severity
high
Software
Kernel
Fixed in
6.11.6
Published
2024-11-07

Affected versions

From: 6.7

Until: 6.11.6

Fixed in: 6.11.6

How to fix this CVE

Update your Linux kernel to version 6.11.6 or later to resolve a buffer overflow vulnerability in SMB2_IOCTL request handling that occurs when encryption is enabled. This fix prevents out-of-bounds writes when processing symlink operations or other CIFS operations with large input buffers over encrypted SMB connections.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version with `uname -r` and verify if it falls in the 6.7–6.11.5 range
  2. Step 2: Confirm CIFS/SMB is in use by checking mounted filesystems with `mount | grep cifs` and verify if 'seal' option or server-enforced encryption is active
  3. Step 3: Search kernel logs for KASAN slab-out-of-bounds errors related to smb2_set_next_command with `dmesg | grep -i 'slab-out-of-bounds\|smb2_set_next_command'`
  4. Step 4: After patching, reboot the system and verify the new kernel is loaded with `uname -r`, confirming version 6.11.6 or later

FAQ

What is CVE-2024-50151?

This vulnerability is a buffer overflow in the Linux kernel's CIFS client when processing SMB2_IOCTL requests over encrypted connections. When a large input buffer (>328 bytes) is passed, the encryption handler overwrites memory beyond the allocated 448-byte buffer, causing a crash or potential code execution.

Is CVE-2024-50151 being actively exploited?

No, this CVE is not currently listed on the CISA KEV catalog and has no public exploits available. However, it can be triggered locally by any user with filesystem access on a system using encrypted CIFS mounts.

What versions of Kernel are affected by CVE-2024-50151?

Linux kernel versions 6.7 through 6.11.5 are vulnerable; version 6.11.6 and later contain the fix.

How do I check if my server is vulnerable to CVE-2024-50151?

Run `uname -r` to check your kernel version. If it shows 6.7.x through 6.11.5, and you have CIFS mounts with 'seal' option or server-enforced encryption (check with `mount | grep cifs`), your system is vulnerable.

Does Defensia detect CVE-2024-50151?

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-2024-50151 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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