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bpf: Refine retval for bpf_get_task_stack helper

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Verifier can constrain the min/max bounds of bpf_get_task_stack's return
value more tightly than the default tnum_unknown. Like bpf_get_stack,
return value is num bytes written into a caller-supplied buf, or error,
so do_refine_retval_range will work.

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210416204704.2816874-2-davemarchevsky@fb.com
This commit is contained in:
Dave Marchevsky
2021-04-16 13:47:02 -07:00
committed by Alexei Starovoitov
parent 137733d08f
commit fd0b88f73f
1 changed files with 1 additions and 0 deletions
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kernel/bpf/verifier.c
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@ -5808,6 +5808,7 @@ static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type,
if (ret_type != RET_INTEGER || if (ret_type != RET_INTEGER ||
(func_id != BPF_FUNC_get_stack && (func_id != BPF_FUNC_get_stack &&
func_id != BPF_FUNC_get_task_stack &&
func_id != BPF_FUNC_probe_read_str && func_id != BPF_FUNC_probe_read_str &&
func_id != BPF_FUNC_probe_read_kernel_str && func_id != BPF_FUNC_probe_read_kernel_str &&
func_id != BPF_FUNC_probe_read_user_str)) func_id != BPF_FUNC_probe_read_user_str))