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nschichanRussell King
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Russell King
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ARM: 7598/1: net: bpf_jit_32: fix sp-relative load/stores offsets.
The offset must be multiplied by 4 to be sure to access the correct 32bit word in the stack scratch space. For instance, a store at scratch memory cell #1 was generating the following: st r4, [sp, #1] While the correct code for this is: st r4, [sp, imx6-dongle#4] To reproduce the bug (assuming your system has a NIC with the mac address 52:54:00:12:34:56): echo 0 > /proc/sys/net/core/bpf_jit_enable tcpdump -ni eth0 "ether[1] + ether[2] - ether[3] * ether[4] - ether[5] \ == -0x3AA" # this will capture packets as expected echo 1 > /proc/sys/net/core/bpf_jit_enable tcpdump -ni eth0 "ether[1] + ether[2] - ether[3] * ether[4] - ether[5] \ == -0x3AA" # this will not. This bug was present since the original inclusion of bpf_jit for ARM (ddecdfc: ARM: 7259/3: net: JIT compiler for packet filters). Signed-off-by: Nicolas Schichan <[email protected]> Signed-off-by: Russell King <[email protected]>
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arch/arm/net/bpf_jit_32.c

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@@ -42,7 +42,7 @@
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#define r_skb_hl ARM_R8
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#define SCRATCH_SP_OFFSET 0
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#define SCRATCH_OFF(k) (SCRATCH_SP_OFFSET + (k))
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#define SCRATCH_OFF(k) (SCRATCH_SP_OFFSET + 4 * (k))
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#define SEEN_MEM ((1 << BPF_MEMWORDS) - 1)
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#define SEEN_MEM_WORD(k) (1 << (k))

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