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    Subject[PATCH AUTOSEL 4.19 307/671] 6lowpan: Off by one handling ->nexthdr
    Date
    From: Dan Carpenter <dan.carpenter@oracle.com>

    [ Upstream commit f57c4bbf34439531adccd7d3a4ecc14f409c1399 ]

    NEXTHDR_MAX is 255. What happens here is that we take a u8 value
    "hdr->nexthdr" from the network and then look it up in
    lowpan_nexthdr_nhcs[]. The problem is that if hdr->nexthdr is 0xff then
    we read one element beyond the end of the array so the array needs to
    be one element larger.

    Fixes: 92aa7c65d295 ("6lowpan: add generic nhc layer interface")
    Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
    Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
    Acked-by: Alexander Aring <aring@mojatatu.com>
    Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/6lowpan/nhc.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/net/6lowpan/nhc.c b/net/6lowpan/nhc.c
    index 4fa2fdda174d..9e56fb98f33c 100644
    --- a/net/6lowpan/nhc.c
    +++ b/net/6lowpan/nhc.c
    @@ -18,7 +18,7 @@
    #include "nhc.h"

    static struct rb_root rb_root = RB_ROOT;
    -static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX];
    +static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX + 1];
    static DEFINE_SPINLOCK(lowpan_nhc_lock);

    static int lowpan_nhc_insert(struct lowpan_nhc *nhc)
    --
    2.20.1
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