s390/bpf: reduce maximum program size to 64 KB

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The s390 BFP compiler currently uses relative branch instructions
that only support jumps up to 64 KB. Examples are "j", "jnz", "cgrj",
etc.  Currently the maximum size of s390 BPF programs is set
to 0x7ffff.  If branches over 64 KB are generated the, kernel can
crash due to incorrect code.

So fix this an reduce the maximum size to 64 KB. Programs larger than
that will be interpreted.

Fixes: ce2b6ad9c1 ("s390/bpf: increase BPF_SIZE_MAX")

Cc: stable@vger.kernel.org # 4.3+
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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Michael Holzheu 2016-05-12 18:10:48 +02:00 • committed by Martin Schwidefsky

parent 2600a46ee0

commit 0fa963553a

1 changed files with 1 additions and 1 deletions

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arch/s390/net/bpf_jit_comp.c

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