On Tue, Sep 2, 2025 at 2:54 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote: > > Hi Ian, > > On Tue, Sep 02, 2025 at 11:17:10AM -0700, Ian Rogers wrote: > > The addition of more use of bpf_prog_info for gather BPF metadata in: > > https://lore.kernel.org/all/20250612194939.162730-1-blakejones@xxxxxxxxxx/ > > and the ever richer perf trace testing, such as: > > https://lore.kernel.org/all/20250528191148.89118-1-howardchu95@xxxxxxxxx/ > > frequently triggered a latent perf bug in v6.17 when the perf and > > libbpf updates came together. The bug would cause segvs and was reported here: > > https://lore.kernel.org/lkml/CAP-5=fWJQcmUOP7MuCA2ihKnDAHUCOBLkQFEkQES-1ZZTrgf8Q@xxxxxxxxxxxxxx/ > > > > To fix the issue the 1st and 3rd patch are necessary. Both patches > > address a race of either the sideband thread updating perf's state or > > the kernel state changing over two system calls. > > Thanks a lot for the fix! Thanks, your reproduction was a great help. > > > > The use-after-free was introduced by: > > https://lore.kernel.org/r/20241205084500.823660-4-quic_zhonhan@xxxxxxxxxxx > > The lack of failing getting the bpf_prog_info for changes in the > > kernel was introduced in: > > https://lore.kernel.org/r/20211011082031.4148337-4-davemarchevsky@xxxxxx > > > > As v6.17 is currently actively segv-ing in perf test I'd recommend > > these patches go into v6.17 asap. > > Sure, I'll add them to perf-tools tree. > > > > > When running the perf tests on v6.17 I frequently see less critical > > test failures addressed in: > > https://lore.kernel.org/all/20250821221834.1312002-1-irogers@xxxxxxxxxx/ > > Are they all from v6.17? We could wait for the backports to v6.17.1, they all have fixes tags. They are more cosmetic things than this set of fixes. Thanks, Ian > > > > > Ian Rogers (3): > > perf bpf-event: Fix use-after-free in synthesis > > perf bpf-utils: Constify bpil_array_desc > > perf bpf-utils: Harden get_bpf_prog_info_linear > > Reviewed-by: Namhyung Kim <namhyung@xxxxxxxxxx> > > Thanks, > Namhyung > > > > > tools/perf/util/bpf-event.c | 39 ++++++++++++++++-------- > > tools/perf/util/bpf-utils.c | 61 ++++++++++++++++++++++++------------- > > 2 files changed, 66 insertions(+), 34 deletions(-) > > > > -- > > 2.51.0.355.g5224444f11-goog > >
