Bug 2402238 (CVE-2023-53660)

Summary: CVE-2023-53660 kernel: bpf, cpumap: Handle skb as well when clean up ptr_ring
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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An incorrect object type handling flaw was found in the Linux kernel's BPF cpumap implementation in the cleanup path. A local user can trigger this issue by running XDP redirect operations in SKB mode with the cpumap, causing the cleanup code to incorrectly treat socket buffers as XDP frames when freeing ptr_ring contents. This results in memory corruption and kernel warnings, leading to denial of service through system instability or crash.
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Description OSIDB Bzimport 2025-10-07 16:04:47 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf, cpumap: Handle skb as well when clean up ptr_ring

The following warning was reported when running xdp_redirect_cpu with
both skb-mode and stress-mode enabled:

  ------------[ cut here ]------------
  Incorrect XDP memory type (-2128176192) usage
  WARNING: CPU: 7 PID: 1442 at net/core/xdp.c:405
  Modules linked in:
  CPU: 7 PID: 1442 Comm: kworker/7:0 Tainted: G  6.5.0-rc2+ #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
  Workqueue: events __cpu_map_entry_free
  RIP: 0010:__xdp_return+0x1e4/0x4a0
  ......
  Call Trace:
   <TASK>
   ? show_regs+0x65/0x70
   ? __warn+0xa5/0x240
   ? __xdp_return+0x1e4/0x4a0
   ......
   xdp_return_frame+0x4d/0x150
   __cpu_map_entry_free+0xf9/0x230
   process_one_work+0x6b0/0xb80
   worker_thread+0x96/0x720
   kthread+0x1a5/0x1f0
   ret_from_fork+0x3a/0x70
   ret_from_fork_asm+0x1b/0x30
   </TASK>

The reason for the warning is twofold. One is due to the kthread
cpu_map_kthread_run() is stopped prematurely. Another one is
__cpu_map_ring_cleanup() doesn't handle skb mode and treats skbs in
ptr_ring as XDP frames.

Prematurely-stopped kthread will be fixed by the preceding patch and
ptr_ring will be empty when __cpu_map_ring_cleanup() is called. But
as the comments in __cpu_map_ring_cleanup() said, handling and freeing
skbs in ptr_ring as well to "catch any broken behaviour gracefully".
Comment 1 Jon Moroney 2025-10-07 17:21:23 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025100702-CVE-2023-53660-92d3@gregkh/T