The faultable variants of bpf_get_stack() and bpf_get_task_stack() pass
may_fault=true into the common stack collection code. Resolving user-space
build IDs may then call build_id_parse_file() and block on filesystem
reads.
Neither helper prototype sets might_sleep. Since prototype selection uses
the sleepability of the whole program, the verifier can still allow these
helpers from a non-sleepable region within that program, such as an
explicit RCU or preemption-disabled region. The task-stack helper can also
be called from a non-sleepable timer callback of a sleepable program.
Mark both faultable prototypes as sleepable. The existing helper context
check then rejects these calls while continuing to allow them in genuinely
sleepable contexts.
Fixes: d4dd9775ec ("bpf: wire up sleepable bpf_get_stack() and bpf_get_task_stack() helpers")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260903214758.2727663-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
9d02927fdf