From: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> [ Upstream commit effe5be17706167ee968fa28afe40dec9c6f71db ] Certain kernel functions (e.g. get_vtimer/set_vtimer) cause kernel panic when the stack is not 8-byte aligned. Currently JITed BPF programs may trigger this by allocating stack frames with non-rounded sizes and then being interrupted. Fix by using rounded fp->aux->stack_depth. Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Link: https://lore.kernel.org/bpf/20200602174339.2501066-1-iii@xxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/s390/net/bpf_jit_comp.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 8d2134136290..0f37a1b635f8 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -594,7 +594,7 @@ static void bpf_jit_epilogue(struct bpf_jit *jit, u32 stack_depth) * stack space for the large switch statement. */ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, - int i, bool extra_pass) + int i, bool extra_pass, u32 stack_depth) { struct bpf_insn *insn = &fp->insnsi[i]; u32 dst_reg = insn->dst_reg; @@ -1207,7 +1207,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, */ if (jit->seen & SEEN_STACK) - off = STK_OFF_TCCNT + STK_OFF + fp->aux->stack_depth; + off = STK_OFF_TCCNT + STK_OFF + stack_depth; else off = STK_OFF_TCCNT; /* lhi %w0,1 */ @@ -1249,7 +1249,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, /* * Restore registers before calling function */ - save_restore_regs(jit, REGS_RESTORE, fp->aux->stack_depth); + save_restore_regs(jit, REGS_RESTORE, stack_depth); /* * goto *(prog->bpf_func + tail_call_start); @@ -1519,7 +1519,7 @@ static int bpf_set_addr(struct bpf_jit *jit, int i) * Compile eBPF program into s390x code */ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp, - bool extra_pass) + bool extra_pass, u32 stack_depth) { int i, insn_count, lit32_size, lit64_size; @@ -1527,18 +1527,18 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp, jit->lit64 = jit->lit64_start; jit->prg = 0; - bpf_jit_prologue(jit, fp->aux->stack_depth); + bpf_jit_prologue(jit, stack_depth); if (bpf_set_addr(jit, 0) < 0) return -1; for (i = 0; i < fp->len; i += insn_count) { - insn_count = bpf_jit_insn(jit, fp, i, extra_pass); + insn_count = bpf_jit_insn(jit, fp, i, extra_pass, stack_depth); if (insn_count < 0) return -1; /* Next instruction address */ if (bpf_set_addr(jit, i + insn_count) < 0) return -1; } - bpf_jit_epilogue(jit, fp->aux->stack_depth); + bpf_jit_epilogue(jit, stack_depth); lit32_size = jit->lit32 - jit->lit32_start; lit64_size = jit->lit64 - jit->lit64_start; @@ -1569,6 +1569,7 @@ struct s390_jit_data { */ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) { + u32 stack_depth = round_up(fp->aux->stack_depth, 8); struct bpf_prog *tmp, *orig_fp = fp; struct bpf_binary_header *header; struct s390_jit_data *jit_data; @@ -1621,7 +1622,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) * - 3: Calculate program size and addrs arrray */ for (pass = 1; pass <= 3; pass++) { - if (bpf_jit_prog(&jit, fp, extra_pass)) { + if (bpf_jit_prog(&jit, fp, extra_pass, stack_depth)) { fp = orig_fp; goto free_addrs; } @@ -1635,7 +1636,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) goto free_addrs; } skip_init_ctx: - if (bpf_jit_prog(&jit, fp, extra_pass)) { + if (bpf_jit_prog(&jit, fp, extra_pass, stack_depth)) { bpf_jit_binary_free(header); fp = orig_fp; goto free_addrs; -- 2.25.1
