{"id":"AZL-68040","summary":"CVE-2025-39905 affecting package kernel 6.6.126.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: phylink: add lock for serializing concurrent pl-\u003ephydev writes with resolver\n\nCurrently phylink_resolve() protects itself against concurrent\nphylink_bringup_phy() or phylink_disconnect_phy() calls which modify\npl-\u003ephydev by relying on pl-\u003estate_mutex.\n\nThe problem is that in phylink_resolve(), pl-\u003estate_mutex is in a lock\ninversion state with pl-\u003ephydev-\u003elock. So pl-\u003ephydev-\u003elock needs to be\nacquired prior to pl-\u003estate_mutex. But that requires dereferencing\npl-\u003ephydev in the first place, and without pl-\u003estate_mutex, that is\nracy.\n\nHence the reason for the extra lock. Currently it is redundant, but it\nwill serve a functional purpose once mutex_lock(&phy-\u003elock) will be\nmoved outside of the mutex_lock(&pl-\u003estate_mutex) section.\n\nAnother alternative considered would have been to let phylink_resolve()\nacquire the rtnl_mutex, which is also held when phylink_bringup_phy()\nand phylink_disconnect_phy() are called. But since phylink_disconnect_phy()\nruns under rtnl_lock(), it would deadlock with phylink_resolve() when\ncalling flush_work(&pl-\u003eresolve). Additionally, it would have been\nundesirable because it would have unnecessarily blocked many other call\npaths as well in the entire kernel, so the smaller-scoped lock was\npreferred.","modified":"2026-04-01T05:21:19.773684Z","published":"2025-10-01T08:15:33Z","upstream":["CVE-2025-39905"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-39905"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.126.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-68040.json"}}],"schema_version":"1.7.5"}