[PATCH] net: x86: bpf: don't forget to free sk_filter (v2)

[PATCH] net: x86: bpf: don't forget to free sk_filter (v2)

[Andrey Vagin]

sk_filter isn't freed if bpf_func is equal to sk_run_filter.

This memory leak was introduced by v3.12-rc3-224-gd45ed4a4
"net: fix unsafe set_memory_rw from softirq".

Before this patch sk_filter was freed in sk_filter_release_rcu,
now it should be freed in bpf_jit_free.

Here is output of kmemleak:
unreferenced object 0xffff8800b774eab0 (size 128):
  comm "systemd", pid 1, jiffies 4294669014 (age 124.062s)
  hex dump (first 32 bytes):
    00 00 00 00 0b 00 00 00 20 63 7f b7 00 88 ff ff  ........ c......
    60 d4 55 81 ff ff ff ff 30 d9 55 81 ff ff ff ff  `.U.....0.U.....
  backtrace:
    [<ffffffff816444be>] kmemleak_alloc+0x4e/0xb0
    [<ffffffff811845af>] __kmalloc+0xef/0x260
    [<ffffffff81534028>] sock_kmalloc+0x38/0x60
    [<ffffffff8155d4dd>] sk_attach_filter+0x5d/0x190
    [<ffffffff815378a1>] sock_setsockopt+0x991/0x9e0
    [<ffffffff81531bd6>] SyS_setsockopt+0xb6/0xd0
    [<ffffffff8165f3e9>] system_call_fastpath+0x16/0x1b
    [<ffffffffffffffff>] 0xffffffffffffffff

v2: add extra { } after else

Fixes: d45ed4a4e33a ("net: fix unsafe set_memory_rw from softirq")
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
---
 arch/x86/net/bpf_jit_comp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 516593e..26328e8 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -788,5 +788,7 @@ void bpf_jit_free(struct sk_filter *fp)
 	if (fp->bpf_func != sk_run_filter) {
 		INIT_WORK(&fp->work, bpf_jit_free_deferred);
 		schedule_work(&fp->work);
+	} else {
+		kfree(fp);
 	}
 }
-- 
1.8.3.1

Re: [PATCH] net: x86: bpf: don't forget to free sk_filter (v2)

[Alexei Starovoitov]

On Wed, Nov 6, 2013 at 8:35 PM, Andrey Vagin <avagin@openvz.org> wrote:
> sk_filter isn't freed if bpf_func is equal to sk_run_filter.
>
> This memory leak was introduced by v3.12-rc3-224-gd45ed4a4
> "net: fix unsafe set_memory_rw from softirq".
>
> Before this patch sk_filter was freed in sk_filter_release_rcu,
> now it should be freed in bpf_jit_free.
>
> Here is output of kmemleak:
> unreferenced object 0xffff8800b774eab0 (size 128):
>   comm "systemd", pid 1, jiffies 4294669014 (age 124.062s)
>   hex dump (first 32 bytes):
>     00 00 00 00 0b 00 00 00 20 63 7f b7 00 88 ff ff  ........ c......
>     60 d4 55 81 ff ff ff ff 30 d9 55 81 ff ff ff ff  `.U.....0.U.....
>   backtrace:
>     [<ffffffff816444be>] kmemleak_alloc+0x4e/0xb0
>     [<ffffffff811845af>] __kmalloc+0xef/0x260
>     [<ffffffff81534028>] sock_kmalloc+0x38/0x60
>     [<ffffffff8155d4dd>] sk_attach_filter+0x5d/0x190
>     [<ffffffff815378a1>] sock_setsockopt+0x991/0x9e0
>     [<ffffffff81531bd6>] SyS_setsockopt+0xb6/0xd0
>     [<ffffffff8165f3e9>] system_call_fastpath+0x16/0x1b
>     [<ffffffffffffffff>] 0xffffffffffffffff
>
> v2: add extra { } after else
>
> Fixes: d45ed4a4e33a ("net: fix unsafe set_memory_rw from softirq")
> Acked-by: Daniel Borkmann <dborkman@redhat.com>
> Cc: Alexei Starovoitov <ast@plumgrid.com>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Signed-off-by: Andrey Vagin <avagin@openvz.org>
> ---

Acked-by: Alexei Starovoitov <ast@plumgrid.com>

Thanks!

Re: [PATCH] net: x86: bpf: don't forget to free sk_filter (v2)

[David Miller]

From: Andrey Vagin <avagin@openvz.org>
Date: Thu,  7 Nov 2013 08:35:12 +0400

> sk_filter isn't freed if bpf_func is equal to sk_run_filter.
> 
> This memory leak was introduced by v3.12-rc3-224-gd45ed4a4
> "net: fix unsafe set_memory_rw from softirq".
> 
> Before this patch sk_filter was freed in sk_filter_release_rcu,
> now it should be freed in bpf_jit_free.
> 
> Here is output of kmemleak:
 ...
> v2: add extra { } after else
> 
> Fixes: d45ed4a4e33a ("net: fix unsafe set_memory_rw from softirq")
> Acked-by: Daniel Borkmann <dborkman@redhat.com>
> Cc: Alexei Starovoitov <ast@plumgrid.com>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Signed-off-by: Andrey Vagin <avagin@openvz.org>

Applied and queued up for -stable, thanks!