FKIE_CVE-2026-74558

Vulnerability from fkie_nvd - Published: 2026-08-15 13:18 - Updated: 2026-08-17 06:19
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: xsk: reclaim invalid Tx descriptors in ZC batch path The zero-copy Tx batch parser stops when it encounters an invalid descriptor. If this happens after one or more continuation descriptors, the Tx consumer can be advanced past fragments that are neither submitted to the driver nor returned to userspace through the completion ring. A similar problem occurs when a packet exceeds xdp_zc_max_segs. The descriptors consumed up to the limit are released without completion, and the remaining continuation descriptors can subsequently be interpreted as the beginning of another packet. Parse Tx batches in packet units and distinguish descriptors belonging to complete valid packets from descriptors consumed while draining an invalid or oversized packet. Return the former to the driver and append the latter to the CQ address area so userspace can reclaim their UMEM frames. Treat a standalone invalid descriptor as a one-descriptor reclaim-only packet. Advancing the Tx-ring consumer releases the ring slot, but does not by itself return ownership of the referenced UMEM frame to userspace. Once draining starts, continue until the packet's end-of-packet descriptor is consumed. Preserve the drain state on the socket when EOP has not yet been supplied, so draining can continue during a later call. Leave incomplete but otherwise valid packets on the Tx ring. Shared-UMEM pools using multi-buffer Tx also need packet-framed parsing. Walk their Tx sockets one packet at a time, preserving the existing per-socket fairness scheme, instead of using the legacy one-descriptor fallback. Keep that fallback for shared pools that do not use multi-buffer Tx. Since the drain state is maintained per socket and both the singular and shared paths can resume an interrupted drain, changing the socket list from singular to shared requires no special bind-time transition. CQ entries are positional, and drivers may complete only part of the Tx work returned by xsk_tx_peek_release_desc_batch(). Therefore, reclaim-only entries cannot be published immediately when earlier driver-visible descriptors are still outstanding. Track the number of driver-visible CQ entries preceding the reclaim entries. Let xsk_tx_completed() publish partial hardware Tx completions, and publish the reclaim entries only after every earlier Tx descriptor has completed. Complete a reclaim-only batch immediately when there is no driver-visible work in front of it, and prevent another Tx batch from being appended while reclaim entries remain pending. Also cap batch processing by the size of the pool's temporary descriptor array, as Tx rings belonging to sockets sharing a UMEM may have different sizes. This ensures that every invalid Tx descriptor consumed by the ZC batch path is either submitted to the driver as part of a valid packet or returned to userspace without violating CQ completion ordering.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/72f2b4516faf55d4dfac2414649d3cffa5fd2c5e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e7ce2bad0c33471c8da4dd73dff2119a68f96f3a
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "Documentation/networking/af_xdp.rst",
            "include/net/xsk_buff_pool.h",
            "net/xdp/xsk.c",
            "net/xdp/xsk_buff_pool.c",
            "net/xdp/xsk_queue.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e7ce2bad0c33471c8da4dd73dff2119a68f96f3a",
              "status": "affected",
              "version": "cf24f5a5feeaae34c1a34d1e04f8ac697290427a",
              "versionType": "git"
            },
            {
              "lessThan": "72f2b4516faf55d4dfac2414649d3cffa5fd2c5e",
              "status": "affected",
              "version": "cf24f5a5feeaae34c1a34d1e04f8ac697290427a",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "Documentation/networking/af_xdp.rst",
            "include/net/xsk_buff_pool.h",
            "net/xdp/xsk.c",
            "net/xdp/xsk_buff_pool.c",
            "net/xdp/xsk_queue.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
            {
              "lessThan": "6.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxsk: reclaim invalid Tx descriptors in ZC batch path\n\nThe zero-copy Tx batch parser stops when it encounters an invalid\ndescriptor. If this happens after one or more continuation descriptors,\nthe Tx consumer can be advanced past fragments that are neither submitted\nto the driver nor returned to userspace through the completion ring.\n\nA similar problem occurs when a packet exceeds xdp_zc_max_segs. The\ndescriptors consumed up to the limit are released without completion, and\nthe remaining continuation descriptors can subsequently be interpreted\nas the beginning of another packet.\n\nParse Tx batches in packet units and distinguish descriptors belonging to\ncomplete valid packets from descriptors consumed while draining an\ninvalid or oversized packet. Return the former to the driver and append\nthe latter to the CQ address area so userspace can reclaim their UMEM\nframes.\n\nTreat a standalone invalid descriptor as a one-descriptor reclaim-only\npacket. Advancing the Tx-ring consumer releases the ring slot, but does\nnot by itself return ownership of the referenced UMEM frame to userspace.\n\nOnce draining starts, continue until the packet\u0027s end-of-packet\ndescriptor is consumed. Preserve the drain state on the socket when EOP\nhas not yet been supplied, so draining can continue during a later call.\nLeave incomplete but otherwise valid packets on the Tx ring.\n\nShared-UMEM pools using multi-buffer Tx also need packet-framed parsing.\nWalk their Tx sockets one packet at a time, preserving the existing\nper-socket fairness scheme, instead of using the legacy one-descriptor\nfallback. Keep that fallback for shared pools that do not use\nmulti-buffer Tx. Since the drain state is maintained per socket and both\nthe singular and shared paths can resume an interrupted drain, changing\nthe socket list from singular to shared requires no special bind-time\ntransition.\n\nCQ entries are positional, and drivers may complete only part of the Tx\nwork returned by xsk_tx_peek_release_desc_batch(). Therefore, reclaim-only\nentries cannot be published immediately when earlier driver-visible\ndescriptors are still outstanding.\n\nTrack the number of driver-visible CQ entries preceding the reclaim\nentries. Let xsk_tx_completed() publish partial hardware Tx completions,\nand publish the reclaim entries only after every earlier Tx descriptor\nhas completed. Complete a reclaim-only batch immediately when there is no\ndriver-visible work in front of it, and prevent another Tx batch from\nbeing appended while reclaim entries remain pending.\n\nAlso cap batch processing by the size of the pool\u0027s temporary descriptor\narray, as Tx rings belonging to sockets sharing a UMEM may have different\nsizes.\n\nThis ensures that every invalid Tx descriptor consumed by the ZC batch\npath is either submitted to the driver as part of a valid packet or\nreturned to userspace without violating CQ completion ordering."
    }
  ],
  "id": "CVE-2026-74558",
  "lastModified": "2026-08-17T06:19:53.910",
  "metrics": {},
  "published": "2026-08-15T13:18:01.267",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/72f2b4516faf55d4dfac2414649d3cffa5fd2c5e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e7ce2bad0c33471c8da4dd73dff2119a68f96f3a"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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