netdev - Re: [PATCH bpf 2/2] bpf, x64: fix memleak when not converging on calls

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Message-Id: <20180502.145401.1482877244354567278.davem@davemloft.net>
Date:   Wed, 02 May 2018 14:54:01 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     daniel@...earbox.net
Cc:     ast@...nel.org, netdev@...r.kernel.org
Subject: Re: [PATCH bpf 2/2] bpf, x64: fix memleak when not converging on
 calls

From: Daniel Borkmann <daniel@...earbox.net>
Date: Wed,  2 May 2018 20:12:23 +0200

> The JIT logic in jit_subprogs() is as follows: for all subprogs we
> allocate a bpf_prog_alloc(), populate it (prog->is_func = 1 here),
> and pass it to bpf_int_jit_compile(). If a failure occurred during
> JIT and prog->jited is not set, then we bail out from attempting to
> JIT the whole program, and punt to the interpreter instead. In case
> JITing went successful, we fixup BPF call offsets and do another
> pass to bpf_int_jit_compile() (extra_pass is true at that point) to
> complete JITing calls. Given that requires to pass JIT context around
> addrs and jit_data from x86 JIT are freed in the extra_pass in
> bpf_int_jit_compile() when calls are involved (if not, they can
> be freed immediately). However, if in the original pass, the JIT
> image didn't converge then we leak addrs and jit_data since image
> itself is NULL, the prog->is_func is set and extra_pass is false
> in that case, meaning both will become unreachable and are never
> cleaned up, therefore we need to free as well on !image. Only x64
> JIT is affected.
> 
> Fixes: 1c2a088a6626 ("bpf: x64: add JIT support for multi-function programs")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Acked-by: Alexei Starovoitov <ast@...nel.org>

Acked-by: David S. Miller <davem@...emloft.net>