Em Thu, Feb 23, 2017 at 11:39:10AM +0000, Reshetova, Elena escreveu: > > Em Wed, Feb 22, 2017 at 08:23:29PM -0300, Arnaldo Carvalho de Melo > > escreveu: > > > Em Tue, Feb 21, 2017 at 12:39:35PM -0300, Arnaldo Carvalho de Melo > > escreveu: > > > > Em Tue, Feb 21, 2017 at 05:34:54PM +0200, Elena Reshetova escreveu: > > > > > Now when new refcount_t type and API are finally merged > > > > > (see include/linux/refcount.h), the following > > > > > patches convert various refcounters in the tools susystem from atomic_t > > > > > to refcount_t. By doing this we prevent intentional or accidental > > > > > underflows or overflows that can led to use-after-free vulnerabilities. > > > > > > > > Thanks for working on this! I was almost going to jump on doing this > > > > myself! > > > > > > > > I'll try and get this merged ASAP. > > > > > > So, please take a look at my tmp.perf/refcount branch at: > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > > I took a look on it and it looks good. Just one thing I want to double check with regards to this commit: > https://kernel.googlesource.com/pub/scm/linux/kernel/git/acme/linux/+/58d561002587bf2572f9e6f4d222659e4068fadf%5E%21/#F0 > > And more specifically to this chunk: > > @@ -937,7 +937,7 @@ > munmap(map->base, perf_mmap__mmap_len(map)); > map->base = NULL; > map->fd = -1; > - atomic_set(&map->refcnt, 0); > + refcount_set(&map->refcnt, 0); > } > auxtrace_mmap__munmap(&map->auxtrace_mmap); > } > So, when the refcount set to zero in this place, what exactly happens > to the perf_map object after? I just want to double check that we > don't have another hiding reusage case here when refcounter later on > is simply incremented vs. set to "2." So, this looks fishy and I don't recall why that was done that way, this conversion to refcnt_t and the debug associated with it provides a good opportunity for us to try to get that to a more familiar reference counting workflow, I'll take a look at it. - Arnaldo > > > There are multiple fixes in it to get it to build and test it, so far, > > > with: > > > > > > perf top -F 15000 -d 0 > > > > > > while doing kernel builds and tight usleep 1 loops to create lots of > > > short lived threads with its map_groups, maps, dsos, etc. > > > > > > Now running some build tests in some 36 containers with assorted distros > > > and cross compilers. > > > > Tomorrow I'll inject some refcount errors to test this all. > > > Thank you! > > Best Regards, > Elena. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
