cbcvebase.
CVE-2022-49093
published 2025-02-26

CVE-2022-49093: 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…

PriorityP338high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.25%
17.0th percentile
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(PAGE

Affected

13 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 5.17.3-1 (bookworm)linux 5.17.3-1 (bookworm)
linuxlinux——
linuxlinux>= 53e0961da1c7bbdabd1abebb20de403ec237ec09 < ba965e8605aee5387cecaa28fcf7ee9f61779a49ba965e8605aee5387cecaa28fcf7ee9f61779a49
linuxlinux>= 53e0961da1c7bbdabd1abebb20de403ec237ec09 < c4fa19615806a9a7e518c295b39175aa47a685acc4fa19615806a9a7e518c295b39175aa47a685ac
linuxlinux>= 53e0961da1c7bbdabd1abebb20de403ec237ec09 < 72bb856d16e883437023ff2ff77d0c498018728a72bb856d16e883437023ff2ff77d0c498018728a
linuxlinux>= 53e0961da1c7bbdabd1abebb20de403ec237ec09 < 1effe8ca4e34c34cdd9318436a4232dcb582ebf41effe8ca4e34c34cdd9318436a4232dcb582ebf4
linuxlinux_kernel——
linuxlinux_kernel>= 0 < 5.17.3-15.17.3-1
linuxlinux_kernel>= 0 < 5.17.3-15.17.3-1
linuxlinux_kernel>= 0 < 5.17.3-15.17.3-1
linuxlinux_kernel>= 5.15 < 5.15.345.15.34
linuxlinux_kernel>= 5.16 < 5.16.205.16.20
linuxlinux_kernel>= 5.17 < 5.17.35.17.3

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
osv7.8HIGH
vendor_debian7.8HIGH
vendor_redhat7.8HIGH
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.