{"id":"CVE-2026-64449","state":"PUBLISHED","title":"staging: vme_user: bound slave read/write to the kern_buf size","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nstaging: vme_user: bound slave read/write to the kern_buf size\n\nThe SLAVE-path helpers buffer_to_user() and buffer_from_user() copy\n'count' bytes into/out of the fixed-size kern_buf (size_buf ==\nPCI_BUF_SIZE == 0x20000, 128 KiB) using *ppos as the offset, without\nbounding *ppos + count against size_buf.\n\nvme_user_write()/vme_user_read() only clamp count to the VME window size\n(image_size = vme_get_size(resource)), which VME_SET_SLAVE sets from the\nuser-supplied slave.size -- validated against the VME address space (up\nto VME_A32_MAX = 4 GiB), not against PCI_BUF_SIZE.  When the window\nexceeds 128 KiB, a write()/read() copies past the kern_buf allocation.\n\nClamp count against size_buf in both helpers, with an early return when\n*ppos is already at/after the buffer end.  *ppos is >= 0 here (the caller\nrejects negative offsets), so size_buf - *ppos cannot wrap.  This mirrors\nthe existing clamp in the MASTER-path helpers resource_to_user() /\nresource_from_user(), and matches the read()/write() convention of a\nshort transfer at end-of-buffer.\n\nFound by static analysis (CodeQL taint tracking + CBMC bounded model\nchecking) and confirmed dynamically under KASAN with the vme_fake bridge:\n\n  BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x2d/0x80\n  Write of size 262144 at addr ffff888004100000 by task trigger/68\n    _copy_from_user+0x2d/0x80\n    vme_user_write+0x13e/0x240 [vme_user]\n    vfs_write+0x1b8/0x7a0\n    ksys_write+0xb8/0x150","publishedAt":"2026-07-25T08:51:19.537Z","updatedAt":"2026-08-17T04:55:52.942Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"65358d89dc9f1c25d9364b2b3ef0f3b47717f9ed","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"adc8b9c30d716c362646edb45662aa1c641a154a","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"8eff7cd4817e14dbe3b9952cce55ef52d1d38940","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"e99f2df433c63c86c93de1e5f08f16e404388756","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"1b495fa0d4927c88d88bf346bf311f2e26e860ed","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"9f32f38265014fac7f5dc9490fb01a638ce6e121","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/staging/vme_user/vme_user.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.32","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.32","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/staging/vme_user/vme_user.c"]}],"references":["https://git.kernel.org/stable/c/65358d89dc9f1c25d9364b2b3ef0f3b47717f9ed","https://git.kernel.org/stable/c/adc8b9c30d716c362646edb45662aa1c641a154a","https://git.kernel.org/stable/c/8eff7cd4817e14dbe3b9952cce55ef52d1d38940","https://git.kernel.org/stable/c/e99f2df433c63c86c93de1e5f08f16e404388756","https://git.kernel.org/stable/c/1b495fa0d4927c88d88bf346bf311f2e26e860ed","https://git.kernel.org/stable/c/9f32f38265014fac7f5dc9490fb01a638ce6e121"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64449.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64449","state":"PUBLISHED","datePublished":"2026-07-25T08:51:19.537Z","dateUpdated":"2026-08-17T04:55:52.942Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.788Z"},"containers":{"cna":{"title":"staging: vme_user: bound slave read/write to the kern_buf size","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nstaging: vme_user: bound slave read/write to the kern_buf size\n\nThe SLAVE-path helpers buffer_to_user() and buffer_from_user() copy\n'count' bytes into/out of the fixed-size kern_buf (size_buf ==\nPCI_BUF_SIZE == 0x20000, 128 KiB) using *ppos as the offset, without\nbounding *ppos + count against size_buf.\n\nvme_user_write()/vme_user_read() only clamp count to the VME window size\n(image_size = vme_get_size(resource)), which VME_SET_SLAVE sets from the\nuser-supplied slave.size -- validated against the VME address space (up\nto VME_A32_MAX = 4 GiB), not against PCI_BUF_SIZE.  When the window\nexceeds 128 KiB, a write()/read() copies past the kern_buf allocation.\n\nClamp count against size_buf in both helpers, with an early return when\n*ppos is already at/after the buffer end.  *ppos is >= 0 here (the caller\nrejects negative offsets), so size_buf - *ppos cannot wrap.  This mirrors\nthe existing clamp in the MASTER-path helpers resource_to_user() /\nresource_from_user(), and matches the read()/write() convention of a\nshort transfer at end-of-buffer.\n\nFound by static analysis (CodeQL taint tracking + CBMC bounded model\nchecking) and confirmed dynamically under KASAN with the vme_fake bridge:\n\n  BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x2d/0x80\n  Write of size 262144 at addr ffff888004100000 by task trigger/68\n    _copy_from_user+0x2d/0x80\n    vme_user_write+0x13e/0x240 [vme_user]\n    vfs_write+0x1b8/0x7a0\n    ksys_write+0xb8/0x150"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"65358d89dc9f1c25d9364b2b3ef0f3b47717f9ed","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"adc8b9c30d716c362646edb45662aa1c641a154a","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"8eff7cd4817e14dbe3b9952cce55ef52d1d38940","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"e99f2df433c63c86c93de1e5f08f16e404388756","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"1b495fa0d4927c88d88bf346bf311f2e26e860ed","versionType":"git"},{"version":"f00a86d98a1ec3e99d352cda926fab767ba43b1f","status":"affected","lessThan":"9f32f38265014fac7f5dc9490fb01a638ce6e121","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/staging/vme_user/vme_user.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.32","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.32","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/staging/vme_user/vme_user.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/65358d89dc9f1c25d9364b2b3ef0f3b47717f9ed"},{"url":"https://git.kernel.org/stable/c/adc8b9c30d716c362646edb45662aa1c641a154a"},{"url":"https://git.kernel.org/stable/c/8eff7cd4817e14dbe3b9952cce55ef52d1d38940"},{"url":"https://git.kernel.org/stable/c/e99f2df433c63c86c93de1e5f08f16e404388756"},{"url":"https://git.kernel.org/stable/c/1b495fa0d4927c88d88bf346bf311f2e26e860ed"},{"url":"https://git.kernel.org/stable/c/9f32f38265014fac7f5dc9490fb01a638ce6e121"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable path is reached through ioctl(), lseek(), read(), and write() on a local /dev/bus/vme/s* character device. Network or physical VME-bus input is not needed.\nAC:L - The attacker can deterministically configure an aligned slave window larger than 128 KiB and select the copy offset and length; no race or external condition is required. A 256 KiB overflow was dynamically confirmed under KASAN.\nPR:L - The driver performs no capability or namespace-specific check, so an ordinary account granted access to the VME device node can configure and trigger the flaw. Although devtmpfs defaults to root-owned mode 0600, non-root access for an industrial control or service account is a reasonable deployment.\nUI:N - The attacker independently performs the configuration and malicious read or write without requiring any victim action.\nS:U - Exploitation compromises the host kernel within the same security authority. This is a standard local privilege-escalation condition, not a VM, sandbox, or IOMMU boundary escape.\nC:H - The read path copies an attacker-selected, potentially very large range of kernel memory beyond the 128 KiB allocation to userspace. This can disclose adjacent allocations, kernel pointers, credentials, and other sensitive memory.\nI:H - The write path copies attacker-controlled bytes beyond the DMA or large-kmalloc allocation, potentially across many adjacent physical pages. This provides exploitable memory corruption capable of modifying kernel objects or achieving control-flow hijacking.\nA:H - The out-of-bounds write was confirmed to trigger a KASAN kernel memory-safety failure and can corrupt or access invalid adjacent memory. A kernel oops or panic can be triggered without user interaction."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:55:52.942Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}