In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix use-after-free in same_client_has_lease()
same_client_has_lease() returns an opinfo pointer from ci->m_op_list after dropping ci->m_lock without taking a reference.
smb_grant_oplock() then dereferences that pointer in copy_lease() and when checking breaking_cnt. A concurrent close can remove the old lease from ci->m_op_list and drop the last reference before the caller uses the returned pointer, leading to a use-after-free.
Take a reference when same_client_has_lease() selects an existing lease, drop any previous match while scanning, and release the returned reference in smb_grant_oplock() after copying the lease state.
References
- https://git.kernel.org/stable/c/09634cd055d9bd8dd167995ea52bcd8028dd5dac
- https://git.kernel.org/stable/c/0ff82a9cf9312678d8bc4edeef0b6e82659ac12a
- https://git.kernel.org/stable/c/35d3d6ff2bc1e7aaecb15d5377ebbd6227acae0d
- https://git.kernel.org/stable/c/65b655f65c3ca1ab5d598d3832bb0ff531725858
- https://git.kernel.org/stable/c/79c7c59bb519db6f5a2a151965e825ec725614cc
- https://git.kernel.org/stable/c/7c3264d273d524aa6adcce23c01087271f13586f
- https://git.kernel.org/stable/c/aaa3bb2bbf2ccbfea9e4e0b9dabf3afc60b50cd0