Subject: Re: [PATCH net 1/2] bpf: rcu lock must not be held when calling copy_to_user()

From: Daniel Borkmann <[email-masked]>
Date: Fri, 23 Jan 2015 11:15:53 +0100

On 01/23/2015 02:11 AM, Alexei Starovoitov wrote:
> BUG: sleeping function called from invalid context at mm/memory.c:3732
> in_atomic(): 0, irqs_disabled(): 0, pid: 671, name: test_maps
> 1 lock held by test_maps/671:
>   #0:  (rcu_read_lock){......}, at: [<0000000000264190>] map_lookup_elem+0xe8/0x260
> Call Trace:
> ([<0000000000115b7e>] show_trace+0x12e/0x150)
>   [<0000000000115c40>] show_stack+0xa0/0x100
>   [<00000000009b163c>] dump_stack+0x74/0xc8
>   [<000000000017424a>] ___might_sleep+0x23a/0x248
>   [<00000000002b58e8>] might_fault+0x70/0xe8
>   [<0000000000264230>] map_lookup_elem+0x188/0x260
>   [<0000000000264716>] SyS_bpf+0x20e/0x840
>
> Fix it by allocating temporary buffer to store map element value.
>
> Fixes: db20fd2b0108 ("bpf: add lookup/update/delete/iterate methods to BPF maps")
> Reported-by: Michael Holzheu <[email-masked]>
> Signed-off-by: Alexei Starovoitov <[email-masked]>

Looks good to me.

Acked-by: Daniel Borkmann <[email-masked]>