From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- lib/test_fpu_impl.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 lib/test_fpu_impl.c (limited to 'lib/test_fpu_impl.c') diff --git a/lib/test_fpu_impl.c b/lib/test_fpu_impl.c new file mode 100644 index 000000000..777894dbb --- /dev/null +++ b/lib/test_fpu_impl.c @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: GPL-2.0+ + +#include + +#include "test_fpu.h" + +int test_fpu(void) +{ + /* + * This sequence of operations tests that rounding mode is + * to nearest and that denormal numbers are supported. + * Volatile variables are used to avoid compiler optimizing + * the calculations away. + */ + volatile double a, b, c, d, e, f, g; + + a = 4.0; + b = 1e-15; + c = 1e-310; + + /* Sets precision flag */ + d = a + b; + + /* Result depends on rounding mode */ + e = a + b / 2; + + /* Denormal and very large values */ + f = b / c; + + /* Depends on denormal support */ + g = a + c * f; + + if (d > a && e > a && g > a) + return 0; + else + return -EINVAL; +} -- cgit v1.3.1