net: bpf: be friendly to kmemcheck

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 <dborkman@redhat.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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 2d1a5b93d91c..6b45f649eff0 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 cfa83cf2447d..0e97ccd29fe3 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 40c53ff59124..cbae2dfd053c 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 b734f975c22e..555f5c7e83ab 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 f7a736b645e8..b2ad9dc5425e 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 9de0b5476b0c..d56cd1f515bd 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 868764fcffb8..4b59edead908 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 fa5b7d0f77ac..dfc716ffa44b 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) {