5.4-stable review patch. If anyone has any objections, please let me know.
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From: Anton Protopopov aspsk@isovalent.com
[ 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@isovalent.com Acked-by: Jiri Olsa jolsa@kernel.org Acked-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/r/20241210114245.836164-1-aspsk@isovalent.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 dde21d23f220..9fb103426cf0 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -496,6 +496,8 @@ 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 */ @@ -503,7 +505,9 @@ 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)