diff mbox series

[v4,bpf-next,6/7] bpf: fix potential error return

Message ID 20241203135052.3380721-7-aspsk@isovalent.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Add fd_array_cnt attribute for BPF_PROG_LOAD | expand

Checks

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bpf/vmtest-bpf-next-PR success PR summary
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 11 maintainers not CCed: sdf@fomichev.me haoluo@google.com eddyz87@gmail.com kpsingh@kernel.org john.fastabend@gmail.com andrii@kernel.org martin.lau@linux.dev yonghong.song@linux.dev song@kernel.org daniel@iogearbox.net ast@kernel.org
netdev/build_clang success Errors and warnings before: 0 this patch: 0
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netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 18 lines checked
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Commit Message

Anton Protopopov Dec. 3, 2024, 1:50 p.m. UTC 
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>
---
 kernel/bpf/core.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Andrii Nakryiko Dec. 3, 2024, 9:26 p.m. UTC | #1 
On Tue, Dec 3, 2024 at 5:49 AM Anton Protopopov <aspsk@isovalent.com> wrote:
>
> 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>
> ---
>  kernel/bpf/core.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>

Looks irrelevant to the patch set and probably should go through the
bpf tree? I'll leave it up to Alexei to decide, though.

Acked-by: Andrii Nakryiko <andrii@kernel.org>


> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index a2327c4fdc8b..8b9711e6da6c 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)
> --
> 2.34.1
>
>
Anton Protopopov Dec. 4, 2024, 10:49 a.m. UTC | #2 
On 24/12/03 01:26PM, Andrii Nakryiko wrote:
> On Tue, Dec 3, 2024 at 5:49 AM Anton Protopopov <aspsk@isovalent.com> wrote:
> >
> > 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>
> > ---
> >  kernel/bpf/core.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> >
> 
> Looks irrelevant to the patch set and probably should go through the
> bpf tree? I'll leave it up to Alexei to decide, though.

Sure, I can send it separately, if needed.

> Acked-by: Andrii Nakryiko <andrii@kernel.org>
> 
> 
> > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> > index a2327c4fdc8b..8b9711e6da6c 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)
> > --
> > 2.34.1
> >
> >
diff mbox series

Patch

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index a2327c4fdc8b..8b9711e6da6c 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)