* [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach
@ 2021-01-11 19:16 Jiri Olsa
2021-01-11 20:03 ` Toke Høiland-Jørgensen
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Jiri Olsa @ 2021-01-11 19:16 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: netdev, bpf, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, Toke Høiland-Jørgensen
The bpf_tracing_prog_attach error path calls bpf_prog_put
on prog, which causes refcount underflow when it's called
from link_create function.
link_create
prog = bpf_prog_get <-- get
...
tracing_bpf_link_attach(prog..
bpf_tracing_prog_attach(prog..
out_put_prog:
bpf_prog_put(prog); <-- put
if (ret < 0)
bpf_prog_put(prog); <-- put
Removing bpf_prog_put call from bpf_tracing_prog_attach
and making sure its callers call it instead.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
kernel/bpf/syscall.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c3bb03c8371f..e5999d86c76e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2712,7 +2712,6 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
out_put_prog:
if (tgt_prog_fd && tgt_prog)
bpf_prog_put(tgt_prog);
- bpf_prog_put(prog);
return err;
}
@@ -2825,7 +2824,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
tp_name = prog->aux->attach_func_name;
break;
}
- return bpf_tracing_prog_attach(prog, 0, 0);
+ err = bpf_tracing_prog_attach(prog, 0, 0);
+ if (err >= 0)
+ return err;
+ goto out_put_prog;
case BPF_PROG_TYPE_RAW_TRACEPOINT:
case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
if (strncpy_from_user(buf,
--
2.26.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach
2021-01-11 19:16 [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach Jiri Olsa
@ 2021-01-11 20:03 ` Toke Høiland-Jørgensen
2021-01-11 20:34 ` Andrii Nakryiko
2021-01-11 23:40 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 6+ messages in thread
From: Toke Høiland-Jørgensen @ 2021-01-11 20:03 UTC (permalink / raw)
To: Jiri Olsa, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: netdev, bpf, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh
Jiri Olsa <jolsa@kernel.org> writes:
> The bpf_tracing_prog_attach error path calls bpf_prog_put
> on prog, which causes refcount underflow when it's called
> from link_create function.
>
> link_create
> prog = bpf_prog_get <-- get
> ...
> tracing_bpf_link_attach(prog..
> bpf_tracing_prog_attach(prog..
> out_put_prog:
> bpf_prog_put(prog); <-- put
>
> if (ret < 0)
> bpf_prog_put(prog); <-- put
>
> Removing bpf_prog_put call from bpf_tracing_prog_attach
> and making sure its callers call it instead.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach
2021-01-11 19:16 [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach Jiri Olsa
2021-01-11 20:03 ` Toke Høiland-Jørgensen
@ 2021-01-11 20:34 ` Andrii Nakryiko
2021-01-11 21:17 ` Jiri Olsa
2021-01-11 23:40 ` patchwork-bot+netdevbpf
2 siblings, 1 reply; 6+ messages in thread
From: Andrii Nakryiko @ 2021-01-11 20:34 UTC (permalink / raw)
To: Jiri Olsa
Cc: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Networking,
bpf, Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Toke Høiland-Jørgensen
On Mon, Jan 11, 2021 at 11:18 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> The bpf_tracing_prog_attach error path calls bpf_prog_put
> on prog, which causes refcount underflow when it's called
> from link_create function.
>
> link_create
> prog = bpf_prog_get <-- get
> ...
> tracing_bpf_link_attach(prog..
> bpf_tracing_prog_attach(prog..
> out_put_prog:
> bpf_prog_put(prog); <-- put
>
> if (ret < 0)
> bpf_prog_put(prog); <-- put
>
> Removing bpf_prog_put call from bpf_tracing_prog_attach
> and making sure its callers call it instead.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
I also double-checked all other attach functions called from
link_create, they all seem to be fine and don't put prog on failure,
so this should be the only needed fix. Also, missing:
Fixes: 4a1e7c0c63e0 ("bpf: Support attaching freplace programs to
multiple attach points")
Acked-by: Andrii Nakryiko <andrii@kernel.org>
> kernel/bpf/syscall.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index c3bb03c8371f..e5999d86c76e 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2712,7 +2712,6 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
> out_put_prog:
> if (tgt_prog_fd && tgt_prog)
> bpf_prog_put(tgt_prog);
> - bpf_prog_put(prog);
> return err;
> }
>
> @@ -2825,7 +2824,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> tp_name = prog->aux->attach_func_name;
> break;
> }
> - return bpf_tracing_prog_attach(prog, 0, 0);
> + err = bpf_tracing_prog_attach(prog, 0, 0);
> + if (err >= 0)
> + return err;
> + goto out_put_prog;
> case BPF_PROG_TYPE_RAW_TRACEPOINT:
> case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
> if (strncpy_from_user(buf,
> --
> 2.26.2
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach
2021-01-11 20:34 ` Andrii Nakryiko
@ 2021-01-11 21:17 ` Jiri Olsa
2021-01-11 21:26 ` Andrii Nakryiko
0 siblings, 1 reply; 6+ messages in thread
From: Jiri Olsa @ 2021-01-11 21:17 UTC (permalink / raw)
To: Andrii Nakryiko
Cc: Jiri Olsa, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Networking, bpf, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, Toke Høiland-Jørgensen
On Mon, Jan 11, 2021 at 12:34:48PM -0800, Andrii Nakryiko wrote:
> On Mon, Jan 11, 2021 at 11:18 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > The bpf_tracing_prog_attach error path calls bpf_prog_put
> > on prog, which causes refcount underflow when it's called
> > from link_create function.
> >
> > link_create
> > prog = bpf_prog_get <-- get
> > ...
> > tracing_bpf_link_attach(prog..
> > bpf_tracing_prog_attach(prog..
> > out_put_prog:
> > bpf_prog_put(prog); <-- put
> >
> > if (ret < 0)
> > bpf_prog_put(prog); <-- put
> >
> > Removing bpf_prog_put call from bpf_tracing_prog_attach
> > and making sure its callers call it instead.
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
>
> I also double-checked all other attach functions called from
> link_create, they all seem to be fine and don't put prog on failure,
> so this should be the only needed fix. Also, missing:
it'd be easier to spot this if we use refcount_t instead of the atomic64_t,
I replaced it for this refcount and got nice console warning for this bug
then I saw:
85192dbf4de0 bpf: Convert bpf_prog refcnt to atomic64_t
so I guess we need something like refcount64_t first
jirka
>
> Fixes: 4a1e7c0c63e0 ("bpf: Support attaching freplace programs to
> multiple attach points")
>
> Acked-by: Andrii Nakryiko <andrii@kernel.org>
>
> > kernel/bpf/syscall.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > index c3bb03c8371f..e5999d86c76e 100644
> > --- a/kernel/bpf/syscall.c
> > +++ b/kernel/bpf/syscall.c
> > @@ -2712,7 +2712,6 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
> > out_put_prog:
> > if (tgt_prog_fd && tgt_prog)
> > bpf_prog_put(tgt_prog);
> > - bpf_prog_put(prog);
> > return err;
> > }
> >
> > @@ -2825,7 +2824,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> > tp_name = prog->aux->attach_func_name;
> > break;
> > }
> > - return bpf_tracing_prog_attach(prog, 0, 0);
> > + err = bpf_tracing_prog_attach(prog, 0, 0);
> > + if (err >= 0)
> > + return err;
> > + goto out_put_prog;
> > case BPF_PROG_TYPE_RAW_TRACEPOINT:
> > case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
> > if (strncpy_from_user(buf,
> > --
> > 2.26.2
> >
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach
2021-01-11 21:17 ` Jiri Olsa
@ 2021-01-11 21:26 ` Andrii Nakryiko
0 siblings, 0 replies; 6+ messages in thread
From: Andrii Nakryiko @ 2021-01-11 21:26 UTC (permalink / raw)
To: Jiri Olsa
Cc: Jiri Olsa, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Networking, bpf, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, Toke Høiland-Jørgensen
On Mon, Jan 11, 2021 at 1:17 PM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Mon, Jan 11, 2021 at 12:34:48PM -0800, Andrii Nakryiko wrote:
> > On Mon, Jan 11, 2021 at 11:18 AM Jiri Olsa <jolsa@kernel.org> wrote:
> > >
> > > The bpf_tracing_prog_attach error path calls bpf_prog_put
> > > on prog, which causes refcount underflow when it's called
> > > from link_create function.
> > >
> > > link_create
> > > prog = bpf_prog_get <-- get
> > > ...
> > > tracing_bpf_link_attach(prog..
> > > bpf_tracing_prog_attach(prog..
> > > out_put_prog:
> > > bpf_prog_put(prog); <-- put
> > >
> > > if (ret < 0)
> > > bpf_prog_put(prog); <-- put
> > >
> > > Removing bpf_prog_put call from bpf_tracing_prog_attach
> > > and making sure its callers call it instead.
> > >
> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > > ---
> >
> > I also double-checked all other attach functions called from
> > link_create, they all seem to be fine and don't put prog on failure,
> > so this should be the only needed fix. Also, missing:
>
> it'd be easier to spot this if we use refcount_t instead of the atomic64_t,
> I replaced it for this refcount and got nice console warning for this bug
>
> then I saw:
> 85192dbf4de0 bpf: Convert bpf_prog refcnt to atomic64_t
>
> so I guess we need something like refcount64_t first
Having a non-failing refcount simplifies code quite a lot. I was
having a problem having to deal with potential refcount failure during
mmap()'ing, where it's impossible to communicate failure back to the
kernel. So if atomic64_t would never fail, but would generate a
warning on underflow, then yeah, it would be an improvement.
>
> jirka
>
> >
> > Fixes: 4a1e7c0c63e0 ("bpf: Support attaching freplace programs to
> > multiple attach points")
> >
> > Acked-by: Andrii Nakryiko <andrii@kernel.org>
> >
> > > kernel/bpf/syscall.c | 6 ++++--
> > > 1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > > index c3bb03c8371f..e5999d86c76e 100644
> > > --- a/kernel/bpf/syscall.c
> > > +++ b/kernel/bpf/syscall.c
> > > @@ -2712,7 +2712,6 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
> > > out_put_prog:
> > > if (tgt_prog_fd && tgt_prog)
> > > bpf_prog_put(tgt_prog);
> > > - bpf_prog_put(prog);
> > > return err;
> > > }
> > >
> > > @@ -2825,7 +2824,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> > > tp_name = prog->aux->attach_func_name;
> > > break;
> > > }
> > > - return bpf_tracing_prog_attach(prog, 0, 0);
> > > + err = bpf_tracing_prog_attach(prog, 0, 0);
> > > + if (err >= 0)
> > > + return err;
> > > + goto out_put_prog;
> > > case BPF_PROG_TYPE_RAW_TRACEPOINT:
> > > case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
> > > if (strncpy_from_user(buf,
> > > --
> > > 2.26.2
> > >
> >
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach
2021-01-11 19:16 [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach Jiri Olsa
2021-01-11 20:03 ` Toke Høiland-Jørgensen
2021-01-11 20:34 ` Andrii Nakryiko
@ 2021-01-11 23:40 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 6+ messages in thread
From: patchwork-bot+netdevbpf @ 2021-01-11 23:40 UTC (permalink / raw)
To: Jiri Olsa
Cc: ast, daniel, andriin, netdev, bpf, kafai, songliubraving, yhs,
john.fastabend, kpsingh, toke
Hello:
This patch was applied to bpf/bpf.git (refs/heads/master):
On Mon, 11 Jan 2021 20:16:50 +0100 you wrote:
> The bpf_tracing_prog_attach error path calls bpf_prog_put
> on prog, which causes refcount underflow when it's called
> from link_create function.
>
> link_create
> prog = bpf_prog_get <-- get
> ...
> tracing_bpf_link_attach(prog..
> bpf_tracing_prog_attach(prog..
> out_put_prog:
> bpf_prog_put(prog); <-- put
>
> [...]
Here is the summary with links:
- bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach
https://git.kernel.org/bpf/bpf/c/5541075a348b
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-01-12 0:30 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2021-01-11 19:16 [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach Jiri Olsa
2021-01-11 20:03 ` Toke Høiland-Jørgensen
2021-01-11 20:34 ` Andrii Nakryiko
2021-01-11 21:17 ` Jiri Olsa
2021-01-11 21:26 ` Andrii Nakryiko
2021-01-11 23:40 ` patchwork-bot+netdevbpf
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