[PATCH bpf v2 0/2] Fix for crash due to overwrite in copy_map_value

[Kumar Kartikeya Dwivedi <memxor@gmail.com>]

A fix for an oversight in copy_map_value that leads to kernel crash.

Also, a question for BPF developers:
It seems in arraymap.c, we always do check_and_free_timer_in_array after we do
copy_map_value in map_update_elem callback, but the same is not done for
hashtab.c. Is there a specific reason for this difference in behavior, or did I
miss that it happens for hashtab.c as well?

Changlog:
---------
v1 -> v2:
v1: https://lore.kernel.org/bpf/20220209051113.870717-1-memxor@gmail.com

 * Fix build error for selftests patch due to missing SYS_PREFIX in bpf tree

Kumar Kartikeya Dwivedi (2):
  bpf: Fix crash due to incorrect copy_map_value
  selftests/bpf: Add test for bpf_timer overwriting crash

 include/linux/bpf.h                           |  3 +-
 .../selftests/bpf/prog_tests/timer_crash.c    | 32 +++++++++++
 .../testing/selftests/bpf/progs/timer_crash.c | 54 +++++++++++++++++++
 3 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/timer_crash.c
 create mode 100644 tools/testing/selftests/bpf/progs/timer_crash.c

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2.35.1