bpf, x86_32: Fix clobbering of dst for BPF_JSET

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: 03f5781be2c7b ("bpf, x86_32: add eBPF JIT compiler for ia32")
Signed-off-by: Xi Wang <[email protected]>
Signed-off-by: Luke Nelson <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Acked-by: Wang YanQing <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

0 files changed, 0 insertions, 0 deletions