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Re: [PATCH 2/2] xen: privcmd: Fix possible access to a freed kirqfd instance
- To: Viresh Kumar <viresh.kumar@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
- From: Juergen Gross <jgross@xxxxxxxx>
- Date: Tue, 2 Jul 2024 12:15:57 +0200
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- Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>, Alex Bennée <alex.bennee@xxxxxxxxxx>, Manos Pitsidianakis <manos.pitsidianakis@xxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, Al Viro <viro@xxxxxxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
- Delivery-date: Tue, 02 Jul 2024 10:16:04 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 18.06.24 11:42, Viresh Kumar wrote:
Nothing prevents simultaneous ioctl calls to privcmd_irqfd_assign() and
privcmd_irqfd_deassign(). If that happens, it is possible that a kirqfd
created and added to the irqfds_list by privcmd_irqfd_assign() may get
removed by another thread executing privcmd_irqfd_deassign(), while the
former is still using it after dropping the locks.
This can lead to a situation where an already freed kirqfd instance may
be accessed and cause kernel oops.
Use SRCU locking to prevent the same, as is done for the KVM
implementation for irqfds.
Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Suggested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Juergen
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