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CVE-2026-31617

usb: gadget: f_ncm: validate minimum block_len in ncm_unwrap_ntb()

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 4.10, 4.15, 4.20, 5.5, 5.9, and 8 more
None on Exploit-DB, Metasploit or GitHub

Summary

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_ncm: validate minimum block_len in ncm_unwrap_ntb() The block_len read from the host-supplied NTB header is checked against ntb_max but has no lower bound. When block_len is smaller than opts->ndp_size, the bounds check of: ndp_index > (block_len - opts->ndp_size) will underflow producing a huge unsigned value that ndp_index can never exceed, defeating the check entirely. The same underflow occurs in the datagram index checks against block_len • opts->dpe_size. With those checks neutered, a malicious USB host can choose ndp_index and datagram offsets that point past the actual transfer, and the skb_put_data() copies adjacent kernel memory into the network skb. Fix this by rejecting block lengths that cannot hold at least the NTB header plus one NDP. This will make block_len - opts->ndp_size and block_len - opts->dpe_size both well-defined. Commit 8d2b1a1ec9f5 ("CDC-NCM: avoid overflow in sanity checking") fixed a related class of issues on the host side of NCM.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 · fixed in 068a7f2749fff6462a0a908ec415b885fe430f50; From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 · fixed in 1425655c2870054c3ab4712e2b6dbdd331597ada; From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 · fixed in 8b3b7bd3c02f98634baaf36c7fc7ac915f6517ca; From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 · fixed in 0f156bb5334e588034ca68ac2ee92b23f66e56e7; From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 · fixed in 8757a2593631443648218244b9788e193ae0fdc1; From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 · fixed in 6762f8a95772265dd0c2ffe7f400493f3115b135; From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 · fixed in d58ba8f6546232f8414f396c189297dbee03f1a7; From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 · fixed in 74908b0318d1df1188457040b8714ff4d4b68126; From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 · fixed in 8f993d30b95dc9557a8a96ceca11abed674c8acb; From 4.9.235 · fixed in 4.10; From 4.14.196 · fixed in 4.15; From 4.19.143 · fixed in 4.20; From 5.4.62 · fixed in 5.5; From 5.8.6 · fixed in 5.9

  • Linux Linux

    5.9

  • KernelLinux

    From 5.9.0 · fixed in 5.10.258; From 5.11.0 · fixed in 5.15.209; From 5.16.0 · fixed in 6.1.175; From 6.2.0 · fixed in 6.6.136; From 6.7.0 · fixed in 6.12.83; From 6.13.0 · fixed in 6.18.24; From 6.19.0 · fixed in 6.19.14; From 6.20.0 · fixed in 7.0.1

References 9

git.kernel.org