CVE-2026-98324 (GCVE-0-2026-98324)
Vulnerability from cvelistv5
Published
2026-10-06 08:46
Modified
2026-10-19 09:17
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: dmaengine: pxa: fix double counting of the hw descriptors pxad_alloc_desc() was converted from kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc), GFP_NOWAIT) to kzalloc_flex(), which sets the __counted_by() counter sw_desc->nb_desc itself - but only where the compiler has __builtin_counted_by_ref(), so from gcc 15.1 or clang 22.1 on. The loop below it still increments nb_desc, which makes it come out doubled there and correct elsewhere. nb_desc is what pxad_free_desc() iterates over and what set_updater_desc() indexes from, so set it explicitly and drop the increment. The error path has to lower it to the number of descriptors allocated so far, otherwise pxad_free_desc() would free entries that were never allocated.
References
Impacted products
Vendor Product Version
Linux Linux Version: 69050f8d6d075dc01af7a5f2f550a8067510366f
Version: 69050f8d6d075dc01af7a5f2f550a8067510366f
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/dma/pxa_dma.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "1de93785f32b450e9eae1e4fcfb7d03eb49eb27e",
              "status": "affected",
              "version": "69050f8d6d075dc01af7a5f2f550a8067510366f",
              "versionType": "git"
            },
            {
              "lessThan": "f6504be006aa4bb4bd26285f410a885c17920d65",
              "status": "affected",
              "version": "69050f8d6d075dc01af7a5f2f550a8067510366f",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/dma/pxa_dma.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.8",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndmaengine: pxa: fix double counting of the hw descriptors\n\npxad_alloc_desc() was converted from\n\n        kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc), GFP_NOWAIT)\n\nto kzalloc_flex(), which sets the __counted_by() counter sw_desc-\u003enb_desc\nitself - but only where the compiler has __builtin_counted_by_ref(), so\nfrom gcc 15.1 or clang 22.1 on. The loop below it still increments\nnb_desc, which makes it come out doubled there and correct elsewhere.\n\nnb_desc is what pxad_free_desc() iterates over and what\nset_updater_desc() indexes from, so set it explicitly and drop the\nincrement. The error path has to lower it to the number of descriptors\nallocated so far, otherwise pxad_free_desc() would free entries that were\nnever allocated."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The fault is in pxad_alloc_desc()/set_updater_desc() in drivers/dma/pxa_dma.c and is triggered by any local I/O that makes a PXA DMA client prep a transfer, e.g. read() on SD/MMC storage via pxamci -\u003e dmaengine_prep_slave_sg() -\u003e pxad_prep_slave_sg(). No remote protocol supplies the bad state.\nAC:L - On builds with gcc\u003e=15.1 or clang\u003e=22.1 (the current default toolchains), kzalloc_flex() already sets nb_desc=N and the loop\u0027s nb_desc++ makes it 2N on every allocation, so every DMA prep overruns hw_desc[]. Controlling the out-of-bounds slot only needs ordinary slab grooming of the neighbouring kmalloc object.\nPR:L - An unprivileged local user can start the vulnerable path just by reading a file on PXA MMC-backed storage (or using SPI/audio devices that use pxa_dma). No capability check sits between the read and pxad_prep_slave_sg().\nUI:N - The attacker drives the I/O that leads to pxad_alloc_desc() and set_updater_desc() through their own syscalls. No victim action is needed.\nS:U - Corruption stays within kernel slab and dma_pool memory under the same kernel authority, with no VM or IOMMU boundary crossed.\nC:H - set_updater_desc(), is_desc_completed() and pxad_residue() read pointers from hw_desc[2N-1] and hw_desc[2N-2], past the kzalloc_flex allocation into adjacent slab memory, and dereference them. A groomed neighbouring object gives a pointer-controlled read.\nI:H - set_updater_desc() writes ddadr/dsadr/dtadr/dcmd (16 bytes) through the out-of-bounds pointer hw_desc[nb_desc-1], and pxad_free_desc() calls dma_pool_free() on up to N out-of-bounds pointers. With a groomed neighbour this is a controlled-address write plus an invalid free.\nA:H - Every pxa_dma transfer dereferences pointers past the allocation and frees nonexistent dma_pool entries in pxad_free_desc(), causing an oops or pool corruption on the first MMC/SPI DMA."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:17:34.749Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/1de93785f32b450e9eae1e4fcfb7d03eb49eb27e"
        },
        {
          "url": "https://git.kernel.org/stable/c/f6504be006aa4bb4bd26285f410a885c17920d65"
        }
      ],
      "title": "dmaengine: pxa: fix double counting of the hw descriptors",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98324",
    "datePublished": "2026-10-06T08:46:17.919Z",
    "dateReserved": "2026-09-25T10:25:14.340Z",
    "dateUpdated": "2026-10-19T09:17:34.749Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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