Messages in this thread |  | | | Date | Sun, 26 Dec 2010 01:46:58 +0300 | | From | Dan Carpenter <> | | Subject | Re: [PATCH] Ceph: Fix a use-after-free bug in ceph_destroy_client(). |
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On Sat, Dec 25, 2010 at 10:24:57PM +0100, Jesper Juhl wrote: > On Sat, 25 Dec 2010, richard -rw- weinberger wrote: > > > On Sat, Dec 25, 2010 at 7:17 PM, Jesper Juhl <jj@chaosbits.net> wrote: > > > Hello, > > > > > > In net/ceph/ceph_common.c::ceph_destroy_client() the pointer 'client' is > > > freed by kfree() and subsequently used in a call to dout() - use after > > > free bug. > > > > Not really. %p reads only the address of "client". > > kfree() does not alter this address. > > > > Ok, I see your point and you are correct. But still, the patch does not > change behaviour and it makes it absolutely clear that there's no > use-after-free bug, so it might still have merit... or? >
I see these with Smatch as well. This type of usage is quite common. People do it deliberately and I guess they feel it's readable. Don't change them.
If it were something that a static checker couldn't figure out, then I'd say change it, but really the static checkers should just be made smarter. Some day I'm going to make Smatch complain if it's a %s in the string instead of a %p, but for now I just ignore the false positives.
regards, dan carpenter
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