* [PATCH bpf-next] bpf: deref map in BPF_PROG_BIND_MAP when it's already used
@ 2020-10-03 0:25 Stanislav Fomichev
2020-10-03 0:35 ` Andrii Nakryiko
2020-10-03 2:25 ` Alexei Starovoitov
0 siblings, 2 replies; 3+ messages in thread
From: Stanislav Fomichev @ 2020-10-03 0:25 UTC (permalink / raw)
To: netdev, bpf; +Cc: davem, ast, daniel, Stanislav Fomichev
We are missing a deref for the case when we are doing BPF_PROG_BIND_MAP
on a map that's being already held by the program.
There is 'if (ret) bpf_map_put(map)' below which doesn't trigger
because we don't consider this an error.
Let's add missing bpf_map_put() for this specific condition.
Fixes: ef15314aa5de ("bpf: Add BPF_PROG_BIND_MAP syscall")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
kernel/bpf/syscall.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index f1528c2a6927..1110ecd7d1f3 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4323,8 +4323,10 @@ static int bpf_prog_bind_map(union bpf_attr *attr)
used_maps_old = prog->aux->used_maps;
for (i = 0; i < prog->aux->used_map_cnt; i++)
- if (used_maps_old[i] == map)
+ if (used_maps_old[i] == map) {
+ bpf_map_put(map);
goto out_unlock;
+ }
used_maps_new = kmalloc_array(prog->aux->used_map_cnt + 1,
sizeof(used_maps_new[0]),
--
2.28.0.806.g8561365e88-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] bpf: deref map in BPF_PROG_BIND_MAP when it's already used
2020-10-03 0:25 [PATCH bpf-next] bpf: deref map in BPF_PROG_BIND_MAP when it's already used Stanislav Fomichev
@ 2020-10-03 0:35 ` Andrii Nakryiko
2020-10-03 2:25 ` Alexei Starovoitov
1 sibling, 0 replies; 3+ messages in thread
From: Andrii Nakryiko @ 2020-10-03 0:35 UTC (permalink / raw)
To: Stanislav Fomichev
Cc: Networking, bpf, David S. Miller, Alexei Starovoitov, Daniel Borkmann
On Fri, Oct 2, 2020 at 5:26 PM Stanislav Fomichev <sdf@google.com> wrote:
>
> We are missing a deref for the case when we are doing BPF_PROG_BIND_MAP
> on a map that's being already held by the program.
> There is 'if (ret) bpf_map_put(map)' below which doesn't trigger
> because we don't consider this an error.
> Let's add missing bpf_map_put() for this specific condition.
>
> Fixes: ef15314aa5de ("bpf: Add BPF_PROG_BIND_MAP syscall")
> Reported-by: Alexei Starovoitov <ast@kernel.org>
> Signed-off-by: Stanislav Fomichev <sdf@google.com>
> ---
Acked-by: Andrii Nakryiko <andriin@fb.com>
> kernel/bpf/syscall.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index f1528c2a6927..1110ecd7d1f3 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -4323,8 +4323,10 @@ static int bpf_prog_bind_map(union bpf_attr *attr)
> used_maps_old = prog->aux->used_maps;
>
> for (i = 0; i < prog->aux->used_map_cnt; i++)
> - if (used_maps_old[i] == map)
> + if (used_maps_old[i] == map) {
> + bpf_map_put(map);
> goto out_unlock;
> + }
>
> used_maps_new = kmalloc_array(prog->aux->used_map_cnt + 1,
> sizeof(used_maps_new[0]),
> --
> 2.28.0.806.g8561365e88-goog
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] bpf: deref map in BPF_PROG_BIND_MAP when it's already used
2020-10-03 0:25 [PATCH bpf-next] bpf: deref map in BPF_PROG_BIND_MAP when it's already used Stanislav Fomichev
2020-10-03 0:35 ` Andrii Nakryiko
@ 2020-10-03 2:25 ` Alexei Starovoitov
1 sibling, 0 replies; 3+ messages in thread
From: Alexei Starovoitov @ 2020-10-03 2:25 UTC (permalink / raw)
To: Stanislav Fomichev
Cc: Network Development, bpf, David S. Miller, Alexei Starovoitov,
Daniel Borkmann
On Fri, Oct 2, 2020 at 5:25 PM Stanislav Fomichev <sdf@google.com> wrote:
>
> We are missing a deref for the case when we are doing BPF_PROG_BIND_MAP
> on a map that's being already held by the program.
> There is 'if (ret) bpf_map_put(map)' below which doesn't trigger
> because we don't consider this an error.
> Let's add missing bpf_map_put() for this specific condition.
>
> Fixes: ef15314aa5de ("bpf: Add BPF_PROG_BIND_MAP syscall")
> Reported-by: Alexei Starovoitov <ast@kernel.org>
> Signed-off-by: Stanislav Fomichev <sdf@google.com>
Thanks for the quick fix! Much appreciated.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-10-03 0:25 [PATCH bpf-next] bpf: deref map in BPF_PROG_BIND_MAP when it's already used Stanislav Fomichev
2020-10-03 0:35 ` Andrii Nakryiko
2020-10-03 2:25 ` Alexei Starovoitov
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