{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98284","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.335Z","datePublished":"2026-10-06T08:45:45.443Z","dateUpdated":"2026-10-06T08:45:45.443Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-06T08:45:45.443Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetlink: do not free nlk->groups while lockless readers can use it\n\nnetlink_realloc_groups() uses krealloc() under netlink_table_grab().\nWhenever NLGRPSZ(groups) lands in a different kmalloc bucket, the old\nbitmap is freed immediately.\n\nTwo readers of nlk->groups / nlk->ngroups do not hold the netlink\ntable lock:\n\n1) sk_diag_dump_groups(). Hashed (bound) sockets are dumped from the\n   rhashtable walk in __netlink_diag_dump(), which only holds RCU.\n   Only the mc_list part of the dump takes nl_table_lock.\n\n2) netlink_native_seq_show() (/proc/net/netlink), whose walk has been\n   lockless since commit 21e4902aea80 (\"netlink: Lockless lookup with\n   RCU grace period in socket release\").\n\nBoth can read a freed buffer, and sk_diag_dump_groups() can also read\npast the end of the old (smaller) buffer if it happens to load the old\n@groups pointer together with the new @ngroups value, copying the\nresult into a NETLINK_DIAG_GROUPS attribute.\n\nThis is the same class of bug that commit f773608026ee (\"netlink:\naccess nlk groups safely in netlink bind and getname\") fixed for bind()\nand getname(); these two readers were missed. Simply grabbing the table\nlock in sk_diag_dump_groups() is not an option, because it is also\ncalled with nl_table_lock already held from the mc_list section of the\ndump.\n\nMake the lockless readers safe instead:\n\n- Allocate a new bitmap and free the old one after an RCU grace period,\n  instead of relying on the implicit kfree() done by krealloc().\n\n- Publish @groups before @ngroups, both with release semantics, and have\n  the lockless readers load @ngroups first. A reader can then never pair\n  the new (bigger) size with the old (smaller) buffer, and a reader\n  picking up the new pointer while still seeing the old size is\n  guaranteed to see the initialized bitmap.\n\nnetlink_realloc_groups() is called from process context (bind() and\nsetsockopt()), so kfree_rcu_mightsleep() can be used, once the table\nhas been released."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netlink/af_netlink.c","net/netlink/diag.c"],"versions":[{"version":"21e4902aea80ef35afc00ee8d2abdea4f519b7f7","lessThan":"22f313e211d58a66786c81487c3905fa5d4b2a8f","status":"affected","versionType":"git"},{"version":"21e4902aea80ef35afc00ee8d2abdea4f519b7f7","lessThan":"ceac0de741bfb47ca255eee075257b3bb31f0651","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netlink/af_netlink.c","net/netlink/diag.c"],"versions":[{"version":"4.0","status":"affected"},{"version":"0","lessThan":"4.0","status":"unaffected","versionType":"semver"},{"version":"7.2.8","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc4","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"7.2.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"7.3-rc4"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/22f313e211d58a66786c81487c3905fa5d4b2a8f"},{"url":"https://git.kernel.org/stable/c/ceac0de741bfb47ca255eee075257b3bb31f0651"}],"title":"netlink: do not free nlk->groups while lockless readers can use it","x_generator":{"engine":"bippy-1.2.0"}}}}