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 --- fs/proc/util.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 fs/proc/util.c (limited to 'fs/proc/util.c') diff --git a/fs/proc/util.c b/fs/proc/util.c new file mode 100644 index 000000000..98f8adc17 --- /dev/null +++ b/fs/proc/util.c @@ -0,0 +1,24 @@ +#include +#include "internal.h" + +unsigned name_to_int(const struct qstr *qstr) +{ + const char *name = qstr->name; + int len = qstr->len; + unsigned n = 0; + + if (len > 1 && *name == '0') + goto out; + do { + unsigned c = *name++ - '0'; + if (c > 9) + goto out; + if (n >= (~0U-9)/10) + goto out; + n *= 10; + n += c; + } while (--len > 0); + return n; +out: + return ~0U; +} -- cgit v1.3.1