From: Anton Protopopov <aspsk@xxxxxxxxxxxxx> [ Upstream commit c4441ca86afe4814039ee1b32c39d833c1a16bbc ] The bpf_remove_insns() function returns WARN_ON_ONCE(error), where error is a result of bpf_adj_branches(), and thus should be always 0 However, if for any reason it is not 0, then it will be converted to boolean by WARN_ON_ONCE and returned to user space as 1, not an actual error value. Fix this by returning the original err after the WARN check. Signed-off-by: Anton Protopopov <aspsk@xxxxxxxxxxxxx> Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Link: https://lore.kernel.org/r/20241210114245.836164-1-aspsk@xxxxxxxxxxxxx Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- kernel/bpf/core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 233ea78f8f1b..3af5f42ea791 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -539,6 +539,8 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, int bpf_remove_insns(struct bpf_prog *prog, u32 off, u32 cnt) { + int err; + /* Branch offsets can't overflow when program is shrinking, no need * to call bpf_adj_branches(..., true) here */ @@ -546,7 +548,9 @@ int bpf_remove_insns(struct bpf_prog *prog, u32 off, u32 cnt) sizeof(struct bpf_insn) * (prog->len - off - cnt)); prog->len -= cnt; - return WARN_ON_ONCE(bpf_adj_branches(prog, off, off + cnt, off, false)); + err = bpf_adj_branches(prog, off, off + cnt, off, false); + WARN_ON_ONCE(err); + return err; } static void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp) -- 2.39.5
