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Re: [PATCH 1/4] fs, afs: convert afs_cell.usage from atomic_t to refcount_t

From David Howells <dhowells@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH 1/4] fs, afs: convert afs_cell.usage from atomic_t to refcount_t
Date 2017-02-22 17:20 +0100
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Elena Reshetova <elena.reshetova@intel.com> wrote:

> refcount_t type and corresponding API should be
> used instead of atomic_t when the variable is used as
> a reference counter. This allows to avoid accidental
> refcounter overflows that might lead to use-after-free
> situations.

This causes an assertion failure because cells aren't immediately destroyed
when their refcount reaches 0, but may be resurrected provided the cache lock
is held.  However, attempting to increment the 0 refcount does nothing, not
even giving a warning.

So please place a hold on this patch.  I will check the other AFS patches also.

David

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Thread

[PATCH 1/4] fs, afs: convert afs_cell.usage from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-02-21 16:50 +0100
  Re: [PATCH 1/4] fs, afs: convert afs_cell.usage from atomic_t to refcount_t David Howells <dhowells@redhat.com> - 2017-02-22 17:20 +0100
    RE: [PATCH 1/4] fs, afs: convert afs_cell.usage from atomic_t to  refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-02-22 18:30 +0100
      Re: [PATCH 1/4] fs, afs: convert afs_cell.usage from atomic_t to refcount_t Kees Cook <keescook@chromium.org> - 2017-02-22 18:40 +0100
        RE: [PATCH 1/4] fs, afs: convert afs_cell.usage from atomic_t to  refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-02-23 14:40 +0100
        Re: [PATCH 1/4] fs, afs: convert afs_cell.usage from atomic_t to refcount_t David Howells <dhowells@redhat.com> - 2017-02-24 15:30 +0100
      Re: [PATCH 1/4] fs, afs: convert afs_cell.usage from atomic_t to refcount_t David Howells <dhowells@redhat.com> - 2017-02-22 18:40 +0100

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