{"id":"CVE-2021-47556","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nethtool: ioctl: fix potential NULL deref in ethtool_set_coalesce()\n\nethtool_set_coalesce() now uses both the .get_coalesce() and\n.set_coalesce() callbacks. But the check for their availability is\nbuggy, so changing the coalesce settings on a device where the driver\nprovides only _one_ of the callbacks results in a NULL pointer\ndereference instead of an -EOPNOTSUPP.\n\nFix the condition so that the availability of both callbacks is\nensured. This also matches the netlink code.\n\nNote that reproducing this requires some effort - it only affects the\nlegacy ioctl path, and needs a specific combination of driver options:\n- have .get_coalesce() and .coalesce_supported but no\n .set_coalesce(), or\n- have .set_coalesce() but no .get_coalesce(). Here eg. ethtool doesn't\n  cause the crash as it first attempts to call ethtool_get_coalesce()\n  and bails out on error.","modified":"2026-03-15T22:43:14.933473Z","published":"2024-05-24T15:15:20.320Z","related":["SUSE-SU-2024:2008-1","SUSE-SU-2024:2011-1","SUSE-SU-2024:2019-1","SUSE-SU-2024:2189-1","SUSE-SU-2024:2190-1"],"references":[{"type":"FIX","url":"https://git.kernel.org/stable/c/abfdd9e2f0f9699015d72317f74154d3e53664e6"},{"type":"FIX","url":"https://git.kernel.org/stable/c/0276af2176c78771da7f311621a25d7608045827"}],"affected":[{"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47556.json","unresolved_ranges":[{"events":[{"introduced":"5.15"},{"fixed":"5.15.6"}]}]}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}