A subprogram returning more than 8 bytes comes back in the R0:R2 register pair, and prepare_func_exit() copies both registers into the caller. The diagnostic modification scope around that copy names only R0, so the write into R2 is never recorded. Fix it by opening a diagnostic modification scope for each return register. This way, both return registers are recorded. Fixes: 0630ad00d96d ("bpf: Add verifier support for 16-byte returns in R0: R2") Signed-off-by: Yonghong Song --- kernel/bpf/verifier.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e036ae20bf6b..9aa29c367008 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10403,10 +10403,14 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) * return to the caller whatever the callee had in the * return register(s) */ - bpf_diag_mod_begin(env, &caller->regs[BPF_REG_0], r0, BPF_DIAG_MOD_WRITE); - for (i = 0; i < nregs; i++) - caller->regs[ret_regs[i]] = callee->regs[ret_regs[i]]; - bpf_diag_mod_end(env); + for (i = 0; i < nregs; i++) { + u32 regno = ret_regs[i]; + + bpf_diag_mod_begin(env, &caller->regs[regno], &callee->regs[regno], + BPF_DIAG_MOD_WRITE); + caller->regs[regno] = callee->regs[regno]; + bpf_diag_mod_end(env); + } } /* for callbacks like bpf_loop or bpf_for_each_map_elem go back to callsite, -- 2.53.0-Meta