Messages in this thread | | | From | Hannes Frederic Sowa <> | Subject | Re: [PATCH net-next v2] net: bpf: make eBPF interpreter images read-only | Date | Tue, 02 Sep 2014 23:43:02 +0200 |
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On Tue, Sep 2, 2014, at 23:40, Eric Dumazet wrote: > On Tue, 2014-09-02 at 14:31 -0700, Alexei Starovoitov wrote: > > > > +static inline void bpf_prog_unlock_ro(struct bpf_prog *fp) > > > +{ > > > + set_memory_rw((unsigned long)fp, fp->pages); > > > > why rw is needed? > > since fp is allocated with vmalloc, vfree doesn't need > > to touch the pages to free them, no? > > That assumes that vmalloc() do not have any debugging features, like > poisoning content before freeing, to catch some use after free. > > Lets be clean and safe, and give back same memory permission we had > after vmalloc()
Yes, I agree. I just went down the kmemleak codepaths and we certainly don't want to cause issues in there if the implementation changes one day.
Bye, Hannes
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