{"id":"CVE-2026-98027","state":"PUBLISHED","title":"net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size\n\nmv88e6xxx_get_rxnfc() uses rxnfc->rule_cnt as the write index while\ndumping the policy IDR, clobbering the input value before it has been\nlooked at.  That input is the number of entries the caller had room for.\nETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the\nbuffer from the rule_cnt userspace passes in, so once an admin has\ninstalled policy rules any user can ask for fewer slots than there are\nrules and run off the end of the allocation.  A rule_cnt of 0 leaves the\nbuffer pointer NULL and the walk dereferences it.\n\nCount into a local so the caller's limit survives the walk, and stop with\n-EMSGSIZE once it is reached.","publishedAt":"2026-09-25T10:23:45.123Z","updatedAt":"2026-10-19T09:12:32.331Z","severity":{"score":7,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/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":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"7e4bfc5f0b66feb22cba821303fc25ca22cd0887","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"01124cd2cf4b71755b1130ac82d78dcfbd5d69e3","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"609c4378f212cf580aae02250f1146caf63d873f","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"c5b5c52b6524c9fb50def2260baac745c095ec3a","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"44cd4674d9aa5bdf793b8a8b481c9e8536ed6070","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"7a683c2b062810bca203e41866389daf387c235b","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"cda5ac8fe8ac8e80b1703ebb8c4250726fc19739","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"b1fffc273112e7284c5b705e186b43b5770cd3d5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/dsa/mv88e6xxx/chip.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.4","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/dsa/mv88e6xxx/chip.c"]}],"references":["https://git.kernel.org/stable/c/7e4bfc5f0b66feb22cba821303fc25ca22cd0887","https://git.kernel.org/stable/c/01124cd2cf4b71755b1130ac82d78dcfbd5d69e3","https://git.kernel.org/stable/c/609c4378f212cf580aae02250f1146caf63d873f","https://git.kernel.org/stable/c/c5b5c52b6524c9fb50def2260baac745c095ec3a","https://git.kernel.org/stable/c/44cd4674d9aa5bdf793b8a8b481c9e8536ed6070","https://git.kernel.org/stable/c/7a683c2b062810bca203e41866389daf387c235b","https://git.kernel.org/stable/c/cda5ac8fe8ac8e80b1703ebb8c4250726fc19739","https://git.kernel.org/stable/c/b1fffc273112e7284c5b705e186b43b5770cd3d5"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98027.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98027","state":"PUBLISHED","datePublished":"2026-09-25T10:23:45.123Z","dateUpdated":"2026-10-19T09:12:32.331Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:19:56.070Z"},"containers":{"cna":{"title":"net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size\n\nmv88e6xxx_get_rxnfc() uses rxnfc->rule_cnt as the write index while\ndumping the policy IDR, clobbering the input value before it has been\nlooked at.  That input is the number of entries the caller had room for.\nETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the\nbuffer from the rule_cnt userspace passes in, so once an admin has\ninstalled policy rules any user can ask for fewer slots than there are\nrules and run off the end of the allocation.  A rule_cnt of 0 leaves the\nbuffer pointer NULL and the walk dereferences it.\n\nCount into a local so the caller's limit survives the walk, and stop with\n-EMSGSIZE once it is reached."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"7e4bfc5f0b66feb22cba821303fc25ca22cd0887","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"01124cd2cf4b71755b1130ac82d78dcfbd5d69e3","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"609c4378f212cf580aae02250f1146caf63d873f","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"c5b5c52b6524c9fb50def2260baac745c095ec3a","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"44cd4674d9aa5bdf793b8a8b481c9e8536ed6070","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"7a683c2b062810bca203e41866389daf387c235b","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"cda5ac8fe8ac8e80b1703ebb8c4250726fc19739","versionType":"git"},{"version":"da7dc87553046a43be1620a783ce3d9f6583d322","status":"affected","lessThan":"b1fffc273112e7284c5b705e186b43b5770cd3d5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/dsa/mv88e6xxx/chip.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.4","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/dsa/mv88e6xxx/chip.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/7e4bfc5f0b66feb22cba821303fc25ca22cd0887"},{"url":"https://git.kernel.org/stable/c/01124cd2cf4b71755b1130ac82d78dcfbd5d69e3"},{"url":"https://git.kernel.org/stable/c/609c4378f212cf580aae02250f1146caf63d873f"},{"url":"https://git.kernel.org/stable/c/c5b5c52b6524c9fb50def2260baac745c095ec3a"},{"url":"https://git.kernel.org/stable/c/44cd4674d9aa5bdf793b8a8b481c9e8536ed6070"},{"url":"https://git.kernel.org/stable/c/7a683c2b062810bca203e41866389daf387c235b"},{"url":"https://git.kernel.org/stable/c/cda5ac8fe8ac8e80b1703ebb8c4250726fc19739"},{"url":"https://git.kernel.org/stable/c/b1fffc273112e7284c5b705e186b43b5770cd3d5"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The overflow is reached only through the local SIOCETHTOOL ioctl: dev_ethtool() -> ethtool_get_rxnfc() -> dsa_user_get_rxnfc() -> mv88e6xxx_get_rxnfc(ETHTOOL_GRXCLSRLALL). The bad input is the rule_cnt field of the ethtool_rxnfc struct the user passes in. No network packet reaches this path.\nAC:H - The OOB write only happens if policy rules already exist in chip->policies for that DSA port. Those are installed by an admin via ETHTOOL_SRXCLSRLINS, which needs CAP_NET_ADMIN over the hardware port. The attacker can't create that state. Once rules exist, a small rule_cnt triggers it deterministically.\nPR:L - dev_ethtool() lists ETHTOOL_GRXCLSRLALL among the commands exempt from the ns_capable(CAP_NET_ADMIN) check. Any unprivileged local user who can see the mv88e6xxx user port in their netns can issue the ioctl.\nUI:N - The attacker makes the ioctl call and picks rule_cnt themselves. No other user has to do anything.\nS:U - The corruption hits the kernel heap in the same kernel that runs the attacker's ioctl. No VM, IOMMU or other authority boundary is crossed.\nC:H - ethtool_get_rxnfc() sizes rule_buf with kcalloc(rule_cnt, 4) from the user's value. The driver then overwrites rxnfc->rule_cnt with the real rule count, so ethtool_rxnfc_copy_to_user() copies that many u32s from the undersized buffer, reading past the slab object into userspace. The same heap corruption can also be groomed to leak more.\nI:H - mv88e6xxx_get_rxnfc() writes rule_locs[rxnfc->rule_cnt++] = id for every rule on the port with no bound, so u32 IDs go past a kmalloc object whose size and cache the attacker chose via rule_cnt. That heap OOB write can corrupt neighbouring objects.\nA:H - With rule_cnt=0, ethtool_get_rxnfc() passes a NULL rule_buf and the IDR walk writes through it, oopsing the kernel on demand. Larger overflows corrupt slab memory and can panic the system. Either can be repeated."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:12:32.331Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.10.271"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"7.2.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}