Messages in this thread Patch in this message | | | Date | Fri, 5 Sep 2014 12:01:59 -0400 (EDT) | From | Mikulas Patocka <> | Subject | [PATCH] bpf: fix a false positive kmemcheck warning |
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This patch fixes false positive kmemcheck warning in bpf.
When we try to write the variable len, the compiler generates a code that reads the 32-bit word, modifies the bits belonging to "len" and writes the 32-bit word back. The reading of the word results in kmemcheck warning due to reading uninitialized memory. This patch fixes it by avoiding using bit fields when kmemcheck is enabled.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
--- include/linux/filter.h | 5 +++++ 1 file changed, 5 insertions(+)
Index: linux-2.6/include/linux/filter.h =================================================================== --- linux-2.6.orig/include/linux/filter.h 2014-09-04 23:04:26.000000000 +0200 +++ linux-2.6/include/linux/filter.h 2014-09-04 23:43:05.000000000 +0200 @@ -325,8 +325,13 @@ struct sock; struct seccomp_data; struct bpf_prog { +#ifdef CONFIG_KMEMCHECK + bool jited; + u32 len; +#else u32 jited:1, /* Is our filter JIT'ed? */ len:31; /* Number of filter blocks */ +#endif struct sock_fprog_kern *orig_prog; /* Original BPF program */ unsigned int (*bpf_func)(const struct sk_buff *skb, const struct bpf_insn *filter);
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