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Sean Christopherson
76021e96d7
KVM: Protect vcpu->pid dereference via debugfs with RCU
Wrap the vcpu->pid dereference in the debugfs hook vcpu_get_pid() with proper RCU read (un)lock. Unlike the code in kvm_vcpu_ioctl(), vcpu_get_pid() is not a simple access; the pid pointer is passed to pid_nr() and fully dereferenced if the pointer is non-NULL. Failure to acquire RCU could result in use-after-free of the old pid if a different task invokes KVM_RUN and puts the last reference to the old vcpu->pid between vcpu_get_pid() reading the pointer and dereferencing it in pid_nr(). Fixes: e36de87d34a7 ("KVM: debugfs: expose pid of vcpu threads") Link: https://lore.kernel.org/r/20230211010719.982919-1-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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