This is a note to let you know that I've just added the patch titled s390/bpf: reduce maximum program size to 64 KB to the 4.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: s390-bpf-reduce-maximum-program-size-to-64-kb.patch and it can be found in the queue-4.6 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 0fa963553a5c28d8f8aabd8878326d3f782045fc Mon Sep 17 00:00:00 2001 From: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx> Date: Thu, 12 May 2016 18:10:48 +0200 Subject: s390/bpf: reduce maximum program size to 64 KB From: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx> commit 0fa963553a5c28d8f8aabd8878326d3f782045fc upstream. 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: ce2b6ad9c185 ("s390/bpf: increase BPF_SIZE_MAX") Signed-off-by: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx> Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/s390/net/bpf_jit_comp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -45,7 +45,7 @@ struct bpf_jit { int labels[1]; /* Labels for local jumps */ }; -#define BPF_SIZE_MAX 0x7ffff /* Max size for program (20 bit signed displ) */ +#define BPF_SIZE_MAX 0xffff /* Max size for program (16 bit branches) */ #define SEEN_SKB 1 /* skb access */ #define SEEN_MEM 2 /* use mem[] for temporary storage */ Patches currently in stable-queue which might be from holzheu@xxxxxxxxxxxxxxxxxx are queue-4.6/s390-bpf-fix-recache-skb-data-hlen-for-skb_vlan_push-pop.patch queue-4.6/s390-bpf-reduce-maximum-program-size-to-64-kb.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html