Files
linux/arch
Luke Nelson f670ee4406 bpf, x86_32: Fix clobbering of dst for BPF_JSET
commit 50fe7ebb64 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
..
2019-02-20 10:25:47 +01:00
2020-05-02 17:25:52 +02:00
2020-02-24 08:34:37 +01:00
2019-12-21 10:57:25 +01:00