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bpf: fix potential error return

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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>
This commit is contained in:
Anton Protopopov 2024-12-10 11:42:45 +00:00 committed by Alexei Starovoitov
parent cf8b876363
commit c4441ca86a
1 changed files with 5 additions and 1 deletions
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6
kernel/bpf/core.c
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@ -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)