Bug 2395311 (CVE-2022-50271)

Summary: CVE-2022-50271 kernel: Linux kernel: Denial of Service due to memory allocation failure in vhost/vsock
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel's vhost/vsock component. A local user could trigger a memory allocation failure when copying large files over sftp (SSH File Transfer Protocol) over vsock (virtual socket). This issue occurs because the kernel's kmalloc function fails to allocate sufficient memory for larger packets, leading to a system crash and a Denial of Service (DoS).
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Description OSIDB Bzimport 2025-09-15 15:06:49 UTC 
In the Linux kernel, the following vulnerability has been resolved:

vhost/vsock: Use kvmalloc/kvfree for larger packets.

When copying a large file over sftp over vsock, data size is usually 32kB,
and kmalloc seems to fail to try to allocate 32 32kB regions.

 vhost-5837: page allocation failure: order:4, mode:0x24040c0
 Call Trace:
  [<ffffffffb6a0df64>] dump_stack+0x97/0xdb
  [<ffffffffb68d6aed>] warn_alloc_failed+0x10f/0x138
  [<ffffffffb68d868a>] ? __alloc_pages_direct_compact+0x38/0xc8
  [<ffffffffb664619f>] __alloc_pages_nodemask+0x84c/0x90d
  [<ffffffffb6646e56>] alloc_kmem_pages+0x17/0x19
  [<ffffffffb6653a26>] kmalloc_order_trace+0x2b/0xdb
  [<ffffffffb66682f3>] __kmalloc+0x177/0x1f7
  [<ffffffffb66e0d94>] ? copy_from_iter+0x8d/0x31d
  [<ffffffffc0689ab7>] vhost_vsock_handle_tx_kick+0x1fa/0x301 [vhost_vsock]
  [<ffffffffc06828d9>] vhost_worker+0xf7/0x157 [vhost]
  [<ffffffffb683ddce>] kthread+0xfd/0x105
  [<ffffffffc06827e2>] ? vhost_dev_set_owner+0x22e/0x22e [vhost]
  [<ffffffffb683dcd1>] ? flush_kthread_worker+0xf3/0xf3
  [<ffffffffb6eb332e>] ret_from_fork+0x4e/0x80
  [<ffffffffb683dcd1>] ? flush_kthread_worker+0xf3/0xf3

Work around by doing kvmalloc instead.
Comment 1 Jon Moroney 2025-09-15 23:09:15 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025091505-CVE-2022-50271-2175@gregkh/T