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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
To:     linux-kernel@vger.kernel.org
Cc:     Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Alexei Starovoitov <ast@kernel.org>,
        Rick Edgecombe <rick.p.edgecombe@intel.com>,
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        Jann Horn <jannh@google.com>,
        Kees Cook <keescook@chromium.org>,
        Jessica Yu <jeyu@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ralf Baechle <ralf@linux-mips.org>,
        Paul Burton <paul.burton@mips.com>,
        James Hogan <jhogan@kernel.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        "David S. Miller" <davem@davemloft.net>,
        linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org,
        linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org,
        netdev@vger.kernel.org
Subject: [PATCH 1/4] bpf: account for freed JIT allocations in arch code
Date:   Sat, 17 Nov 2018 10:57:12 -0800
Message-Id: <20181117185715.25198-2-ard.biesheuvel@linaro.org>
In-Reply-To: <20181117185715.25198-1-ard.biesheuvel@linaro.org>
References: <20181117185715.25198-1-ard.biesheuvel@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Commit ede95a63b5e84 ("bpf: add bpf_jit_limit knob to restrict unpriv
allocations") added a call to bpf_jit_uncharge_modmem() to the routine
bpf_jit_binary_free() which is called from the __weak bpf_jit_free().
This function is overridden by arches, some of which do not call
bpf_jit_binary_free() to release the memory, and so the released
memory is not accounted for, potentially leading to spurious allocation
failures.

So replace the direct calls to module_memfree() in the arch code with
calls to bpf_jit_binary_free().

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 arch/mips/net/bpf_jit.c           | 2 +-
 arch/powerpc/net/bpf_jit_comp.c   | 2 +-
 arch/powerpc/net/bpf_jit_comp64.c | 5 +----
 arch/sparc/net/bpf_jit_comp_32.c  | 2 +-
 4 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
index 4d8cb9bb8365..1b69897274a1 100644
--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c
@@ -1264,7 +1264,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
 void bpf_jit_free(struct bpf_prog *fp)
 {
 	if (fp->jited)
-		module_memfree(fp->bpf_func);
+		bpf_jit_binary_free(bpf_jit_binary_hdr(fp));
 
 	bpf_prog_unlock_free(fp);
 }
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index d5bfe24bb3b5..a1ea1ea6b40d 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -683,7 +683,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
 void bpf_jit_free(struct bpf_prog *fp)
 {
 	if (fp->jited)
-		module_memfree(fp->bpf_func);
+		bpf_jit_binary_free(bpf_jit_binary_hdr(fp));
 
 	bpf_prog_unlock_free(fp);
 }
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 50b129785aee..84c8f013a6c6 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -1024,11 +1024,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
 /* Overriding bpf_jit_free() as we don't set images read-only. */
 void bpf_jit_free(struct bpf_prog *fp)
 {
-	unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
-	struct bpf_binary_header *bpf_hdr = (void *)addr;
-
 	if (fp->jited)
-		bpf_jit_binary_free(bpf_hdr);
+		bpf_jit_binary_free(bpf_jit_binary_hdr(fp));
 
 	bpf_prog_unlock_free(fp);
 }
diff --git a/arch/sparc/net/bpf_jit_comp_32.c b/arch/sparc/net/bpf_jit_comp_32.c
index a5ff88643d5c..01bda6bc9e7f 100644
--- a/arch/sparc/net/bpf_jit_comp_32.c
+++ b/arch/sparc/net/bpf_jit_comp_32.c
@@ -759,7 +759,7 @@ cond_branch:			f_offset = addrs[i + filter[i].jf];
 void bpf_jit_free(struct bpf_prog *fp)
 {
 	if (fp->jited)
-		module_memfree(fp->bpf_func);
+		bpf_jit_binary_free(bpf_jit_binary_hdr(fp));
 
 	bpf_prog_unlock_free(fp);
 }
-- 
2.17.1