In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix use-after-free of signing key
Customers have reported use-after-free in @ses->auth_key.response with SMB2.1 + sign mounts which occurs due to following race:
task A task B cifsmount() dfsmountshare() getsession() cifsmountgetsession() cifssendrecv() cifsgetsmbses() compoundsendrecv() cifssetupsession() smb2setuprequest() kfreesensitive() smb2calcsignature() cryptoshash_setkey() UAF
Fix this by ensuring that we have a valid @ses->authkey.response by checking whether @ses->sesstatus is SESGOOD or SESEXITING with @ses->seslock held. After commit 24a9799aa8ef ("smb: client: fix UAF in smb2reconnectserver()"), we made sure to call ->logoff() only when @ses was known to be good (e.g. valid ->authkey.response), so it's safe to access signing key when @ses->sesstatus == SESEXITING.