# CVE-2022-49093: linux: In the Linux kernel, the following vulnerability has been resolved: skbuff: fix coalescing for page_pool fragment re... CVE-2022-49093 is fixed in 27 products on 1 platform, first by RHSA-2022:8267, released November 15, 2022. It is not reported as exploited. Patch Radar priority: Urgent. - Web page: https://patchblox.com/security/cve/CVE-2022-49093 - Priority: Urgent - CVSS: 9.8 (critical) - EPSS: 0.0063 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Nov 15, 2022 ## Description In the Linux kernel, the following vulnerability has been resolved: skbuff: fix coalescing for page_pool fragment recycling Fix a use-after-free when using page_pool with page fragments. We encountered this problem during normal RX in the hns3 driver: (1) Initially we have three descriptors in the RX queue. The first one allocates PAGE1 through page_pool, and the other two allocate one half of PAGE2 each. Page references look like this: RX_BD1 _______ PAGE1 RX_BD2 _______ PAGE2 RX_BD3 _________/ (2) Handle RX on the first descriptor. Allocate SKB1, eventually added to the receive queue by tcp_queue_rcv(). (3) Handle RX on the second descriptor. Allocate SKB2 and pass it to netif_receive_skb(): netif_receive_skb(SKB2) ip_rcv(SKB2) SKB3 = skb_clone(SKB2) SKB2 and SKB3 share a reference to PAGE2 through skb_shinfo()->dataref. The other ref to PAGE2 is still held by RX_BD3: SKB2 ---+- PAGE2 SKB3 __/ / RX_BD3 _________/ (3b) Now while handling TCP, coalesce SKB3 with SKB1: tcp_v4_rcv(SKB3) tcp_try_coalesce(to=SKB1, from=SKB3) // succeeds kfree_skb_partial(SKB3) skb_release_data(SKB3) // drops one dataref SKB1 _____ PAGE1 \____ SKB2 _____ PAGE2 / RX_BD3 _________/ In skb_try_coalesce(), __skb_frag_ref() takes a page reference to PAGE2, where it should instead have increased the page_pool frag reference, pp_frag_count. Without coalescing, when releasing both SKB2 and SKB3, a single reference to PAGE2 would be dropped. Now when releasing SKB1 and SKB2, two references to PAGE2 will be dropped, resulting in underflow. (3c) Drop SKB2: af_packet_rcv(SKB2) consume_skb(SKB2) skb_release_data(SKB2) // drops second dataref page_pool_return_skb_page(PAGE2) // drops one pp_frag_count SKB1 _____ PAGE1 \____ PAGE2 / RX_BD3 _________/ (4) Userspace calls recvmsg() Copies SKB1 and releases it. Since SKB3 was coalesced with SKB1, we release the SKB3 page as well: tcp_eat_recv_skb(SKB1) skb_release_data(SKB1) page_pool_return_skb_page(PAGE1) page_pool_return_skb_page(PAGE2) // drops second pp_frag_count (5) PAGE2 is freed, but the third RX descriptor was still using it! In our case this causes IOMMU faults, but it would silently corrupt memory if the IOMMU was disabled. Change the logic that checks whether pp_recycle SKBs can be coalesced. We still reject differing pp_recycle between 'from' and 'to' SKBs, but in order to avoid the situation described above, we also reject coalescing when both 'from' and 'to' are pp_recycled and 'from' is cloned. The new logic allows coalescing a cloned pp_recycle SKB into a page refcounted one, because in this case the release (4) will drop the right reference, the one taken by skb_try_coalesce(). ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-abi-stablelists RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-core RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-debug RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-debug-core RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-debug-devel RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-debug-devel-matched RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-debug-modules RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-debug-modules-extra RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-devel RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-devel-matched RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-doc RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-modules RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-modules-extra RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-tools RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-tools-libs RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-tools-libs-devel RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-zfcpdump RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-zfcpdump-core RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-zfcpdump-devel RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-zfcpdump-devel-matched RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-zfcpdump-modules RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | kernel-zfcpdump-modules-extra RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | linux Debian 12.15 (bookworm) | 5.17.3-1 | [DEBIAN-CVE-2022-49093](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49093.md) | Feb 26, 2025 | | Linux | linux Debian 13.5 (trixie) | 5.17.3-1 | [DEBIAN-CVE-2022-49093](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49093.md) | Feb 26, 2025 | | Linux | linux Debian 14 | 5.17.3-1 | [DEBIAN-CVE-2022-49093](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49093.md) | Feb 26, 2025 | | Linux | perf RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | | Linux | python3-perf RHEL 9 | 0:5.14.0-162.6.1.el9_1 | [RHSA-2022:8267](https://patchblox.com/security/data/fix/linux/rhsa-2022-8267.md) | Nov 15, 2022 | --- Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.