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ARM: net: fix condition for load_order > 0 when translating load instructions.

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To check whether the load should take the fast path or not, the code
would check that (r_skb_hlen - load_order) is greater than the offset
of the access using an "Unsigned higher or same" condition. For
halfword accesses and an skb length of 1 at offset 0, that test is
valid, as we end up comparing 0xffffffff(-1) and 0, so the fast path
is taken and the filter allows the load to wrongly succeed. A similar
issue exists for word loads at offset 0 and an skb length of less than
4.

Fix that by using the condition "Signed greater than or equal"
condition for the fast path code for load orders greater than 0.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Nicolas Schichan 2015-07-21 14:14:12 +02:00 committed by David S. Miller
parent 89e478a2aa
commit 7aed35cb65
1 changed files with 1 additions and 1 deletions
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arch/arm/net/bpf_jit_32.c
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@ -547,7 +547,7 @@ static int build_body(struct jit_ctx *ctx)
emit(ARM_SUB_I(r_scratch, r_skb_hl,
1 << load_order), ctx);
emit(ARM_CMP_R(r_scratch, r_off), ctx);
condt = ARM_COND_HS;
condt = ARM_COND_GE;
} else {
emit(ARM_CMP_R(r_skb_hl, r_off), ctx);
condt = ARM_COND_HI;