On Fri, May 01, 2020 at 11:42:28AM +0800, Wang YanQing wrote:
On Fri, May 01, 2020 at 11:19:50AM +0800, Wang YanQing wrote:
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: 03f5781be2c7b ("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
Cc: stable@vger.kernel.org #v4.19
Now queued up, thanks.
greg k-h