CVE-2022-49093: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-3j29-8r33-hfrc",
  "modified" : "2025-02-27T21:32:11Z",
  "published" : "2025-02-27T21:32:11Z",
  "aliases" : [ "CVE-2022-49093" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nskbuff: fix coalescing for page_pool fragment recycling\n\nFix a use-after-free when using page_pool with page fragments. We\nencountered this problem during normal RX in the hns3 driver:\n\n(1) Initially we have three descriptors in the RX queue. The first one\n    allocates PAGE1 through page_pool, and the other two allocate one\n    half of PAGE2 each. Page references look like this:\n\n                RX_BD1 _______ PAGE1\n                RX_BD2 _______ PAGE2\n                RX_BD3 _________/\n\n(2) Handle RX on the first descriptor. Allocate SKB1, eventually added\n    to the receive queue by tcp_queue_rcv().\n\n(3) Handle RX on the second descriptor. Allocate SKB2 and pass it to\n    netif_receive_skb():\n\n    netif_receive_skb(SKB2)\n      ip_rcv(SKB2)\n        SKB3 = skb_clone(SKB2)\n\n    SKB2 and SKB3 share a reference to PAGE2 through\n    skb_shinfo()->dataref. The other ref to PAGE2 is still held by\n    RX_BD3:\n\n                      SKB2 ---+- PAGE2\n                      SKB3 __/   /\n                RX_BD3 _________/\n\n (3b) Now while handling TCP, coalesce SKB3 with SKB1:\n\n      tcp_v4_rcv(SKB3)\n        tcp_try_coalesce(to=SKB1, from=SKB3)    // succeeds\n        kfree_skb_partial(SKB3)\n          skb_release_data(SKB3)                // drops one dataref\n\n                      SKB1 _____ PAGE1\n                           \\____\n                      SKB2 _____ PAGE2\n                                 /\n                RX_BD3 _________/\n\n    In skb_try_coalesce(), __skb_frag_ref() takes a page reference to\n    PAGE2, where it should instead have increased the page_pool frag\n    reference, pp_frag_count. Without coalescing, when releasing both\n    SKB2 and SKB3, a single reference to PAGE2 would be dropped. Now\n    when releasing SKB1 and SKB2, two references to PAGE2 will be\n    dropped, resulting in underflow.\n\n (3c) Drop SKB2:\n\n      af_packet_rcv(SKB2)\n        consume_skb(SKB2)\n          skb_release_data(SKB2)                // drops second dataref\n            page_pool_return_skb_page(PAGE2)    // drops one pp_frag_count\n\n                      SKB1 _____ PAGE1\n                           \\____\n                                 PAGE2\n                                 /\n                RX_BD3 _________/\n\n(4) Userspace calls recvmsg()\n    Copies SKB1 and releases it. Since SKB3 was coalesced with SKB1, we\n    release the SKB3 page as well:\n\n    tcp_eat_recv_skb(SKB1)\n      skb_release_data(SKB1)\n        page_pool_return_skb_page(PAGE1)\n        page_pool_return_skb_page(PAGE2)        // drops second pp_frag_count\n\n(5) PAGE2 is freed, but the third RX descriptor was still using it!\n    In our case this causes IOMMU faults, but it would silently corrupt\n    memory if the IOMMU was disabled.\n\nChange the logic that checks whether pp_recycle SKBs can be coalesced.\nWe still reject differing pp_recycle between 'from' and 'to' SKBs, but\nin order to avoid the situation described above, we also reject\ncoalescing when both 'from' and 'to' are pp_recycled and 'from' is\ncloned.\n\nThe new logic allows coalescing a cloned pp_recycle SKB into a page\nrefcounted one, because in this case the release (4) will drop the right\nreference, the one taken by skb_try_coalesce().",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2022-49093"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/1effe8ca4e34c34cdd9318436a4232dcb582ebf4"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/72bb856d16e883437023ff2ff77d0c498018728a"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/ba965e8605aee5387cecaa28fcf7ee9f61779a49"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/c4fa19615806a9a7e518c295b39175aa47a685ac"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-416" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2025-02-26T07:00:46Z"
  }
}