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xfs: Don't reference the EFI after it is freed 

Checking the EFI for whether it is being released from recovery
after we've already released the known active reference is a mistake
worthy of a brown paper bag. Fix the (now) obvious use after free
that it can cause.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

(cherry picked from commit 52c24ad39f)
This commit is contained in:
Dave Chinner 2013-05-20 09:51:10 +10:00 committed by Ben Myers
parent 7031d0e1c4
commit 509e708a89
1 changed files with 3 additions and 2 deletions
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5
fs/xfs/xfs_extfree_item.c
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@ -305,11 +305,12 @@ xfs_efi_release(xfs_efi_log_item_t *efip,
{
ASSERT(atomic_read(&efip->efi_next_extent) >= nextents);
if (atomic_sub_and_test(nextents, &efip->efi_next_extent)) {
__xfs_efi_release(efip);
/* recovery needs us to drop the EFI reference, too */
if (test_bit(XFS_EFI_RECOVERED, &efip->efi_flags))
__xfs_efi_release(efip);
__xfs_efi_release(efip);
/* efip may now have been freed, do not reference it again. */
}
}