Luke Nelson f670ee4406 bpf, x86_32: Fix clobbering of dst for BPF_JSET ... commit 50fe7ebb6475711c15b3397467e6424e20026d94 upstream. The current JIT clobbers the destination register for BPF_JSET BPF_X and BPF_K by using "and" and "or" instructions. This is fine when the destination register is a temporary loaded from a register stored on the stack but not otherwise. This patch fixes the problem (for both BPF_K and BPF_X) by always loading the destination register into temporaries since BPF_JSET should not modify the destination register. This bug may not be currently triggerable as BPF_REG_AX is the only register not stored on the stack and the verifier uses it in a limited way. Fixes: 03f5781be2 ("bpf, x86_32: add eBPF JIT compiler for ia32") Signed-off-by: Xi Wang <xi.wang@gmail.com> Signed-off-by: Luke Nelson <luke.r.nels@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Wang YanQing <udknight@gmail.com> Link: https://lore.kernel.org/bpf/20200422173630.8351-2-luke.r.nels@gmail.com Signed-off-by: Wang YanQing <udknight@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-05-02 17:26:00 +02:00
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bpf_jit_comp.c	bpf, x86: Fix encoding for lower 8-bit registers in BPF_STX BPF_B	2020-05-02 17:25:54 +02:00
bpf_jit_comp32.c	bpf, x86_32: Fix clobbering of dst for BPF_JSET	2020-05-02 17:26:00 +02:00
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