[PATCH net-next 3/3] net: bpf: be friendly to kmemcheck

From: Daniel Borkmann <hidden>
Date: 2014-09-06 09:43:00
Subsystem: arm port, bpf jit for arm, bpf jit for mips (32-bit and 64-bit), bpf jit for powerpc (32-bit and 64-bit), bpf jit for s390, bpf jit for sparc (32-bit and 64-bit), bpf jit for x86 64-bit, bpf [core], bpf [general] (safe dynamic programs and tools), bpf [networking] (tcx & tc bpf, sock_addr), linux for powerpc (32-bit and 64-bit), mips, networking [general], s390 architecture, sparc + ultrasparc (sparc/sparc64), the rest, x86 architecture (32-bit and 64-bit) · Maintainers: Russell King, Puranjay Mohan, Johan Almbladh, Paul Burton, Hari Bathini, Christophe Leroy, Ilya Leoshkevich, Heiko Carstens, Vasily Gorbik, David S. Miller, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Martin KaFai Lau, Madhavan Srinivasan, Michael Ellerman, Thomas Bogendoerfer, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Alexander Gordeev, Andreas Larsson, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen

Reported by Mikulas Patocka, kmemcheck currently barks out a
false positive since we don't have special kmemcheck annotation
for bitfields used in bpf_prog structure.

We currently have jited:1, len:31 and thus when accessing len
while CONFIG_KMEMCHECK enabled, kmemcheck throws a warning that
we're reading uninitialized memory.

As we don't need the whole bit universe for pages member, we
can just split it to u16 and use a bool flag for jited instead
of a bitfield.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Daniel Borkmann <redacted>
Cc: Alexei Starovoitov <redacted>
---
 arch/arm/net/bpf_jit_32.c       | 2 +-
 arch/mips/net/bpf_jit.c         | 2 +-
 arch/powerpc/net/bpf_jit_comp.c | 2 +-
 arch/s390/net/bpf_jit_comp.c    | 2 +-
 arch/sparc/net/bpf_jit_comp.c   | 2 +-
 arch/x86/net/bpf_jit_comp.c     | 2 +-
 include/linux/filter.h          | 6 +++---
 net/core/filter.c               | 2 +-
 8 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index 2d1a5b9..6b45f64 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c

@@ -933,7 +933,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
 
 	set_memory_ro((unsigned long)header, header->pages);
 	fp->bpf_func = (void *)ctx.target;
-	fp->jited = 1;
+	fp->jited = true;
 out:
 	kfree(ctx.offsets);
 	return;

diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
index cfa83cf..0e97ccd 100644
--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c

@@ -1417,7 +1417,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
 		bpf_jit_dump(fp->len, alloc_size, 2, ctx.target);
 
 	fp->bpf_func = (void *)ctx.target;
-	fp->jited = 1;
+	fp->jited = true;
 
 out:
 	kfree(ctx.offsets);

diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 40c53ff..cbae2df 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c

@@ -686,7 +686,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
 		((u64 *)image)[0] = (u64)code_base;
 		((u64 *)image)[1] = local_paca->kernel_toc;
 		fp->bpf_func = (void *)image;
-		fp->jited = 1;
+		fp->jited = true;
 	}
 out:
 	kfree(addrs);

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index b734f97..555f5c7 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c

@@ -842,7 +842,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
 	if (jit.start) {
 		set_memory_ro((unsigned long)header, header->pages);
 		fp->bpf_func = (void *) jit.start;
-		fp->jited = 1;
+		fp->jited = true;
 	}
 out:
 	kfree(addrs);

diff --git a/arch/sparc/net/bpf_jit_comp.c b/arch/sparc/net/bpf_jit_comp.c
index f7a736b..b2ad9dc 100644
--- a/arch/sparc/net/bpf_jit_comp.c
+++ b/arch/sparc/net/bpf_jit_comp.c

@@ -801,7 +801,7 @@ cond_branch:			f_offset = addrs[i + filter[i].jf];
 	if (image) {
 		bpf_flush_icache(image, image + proglen);
 		fp->bpf_func = (void *)image;
-		fp->jited = 1;
+		fp->jited = true;
 	}
 out:
 	kfree(addrs);

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 9de0b54..d56cd1f 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c

@@ -955,7 +955,7 @@ void bpf_int_jit_compile(struct bpf_prog *prog)
 		bpf_flush_icache(header, image + proglen);
 		set_memory_ro((unsigned long)header, header->pages);
 		prog->bpf_func = (void *)image;
-		prog->jited = 1;
+		prog->jited = true;
 	}
 out:
 	kfree(addrs);

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 868764f..4b59ede 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h

@@ -300,9 +300,9 @@ struct bpf_work_struct {
 };
 
 struct bpf_prog {
-	u32			pages;		/* Number of allocated pages */
-	u32			jited:1,	/* Is our filter JIT'ed? */
-				len:31;		/* Number of filter blocks */
+	u16			pages;		/* Number of allocated pages */
+	bool			jited;		/* Is our filter JIT'ed? */
+	u32			len;		/* Number of filter blocks */
 	struct sock_fprog_kern	*orig_prog;	/* Original BPF program */
 	struct bpf_work_struct	*work;		/* Deferred free work struct */
 	unsigned int		(*bpf_func)(const struct sk_buff *skb,

diff --git a/net/core/filter.c b/net/core/filter.c
index fa5b7d0..dfc716f 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c

@@ -972,7 +972,7 @@ static struct bpf_prog *bpf_prepare_filter(struct bpf_prog *fp)
 	int err;
 
 	fp->bpf_func = NULL;
-	fp->jited = 0;
+	fp->jited = false;
 
 	err = bpf_check_classic(fp->insns, fp->len);
 	if (err) {

-- 
1.7.11.7

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