From cd1231d7035fea894118d5155ff984cdaf1ac1a2 Mon Sep 17 00:00:00 2001 From: Madhavan Srinivasan Date: Wed, 21 Mar 2018 17:10:26 +0530 Subject: [PATCH] powerpc/perf: Prevent kernel address leak via perf_get_data_addr() Sampled Data Address Register (SDAR) is a 64-bit register that contains the effective address of the storage operand of an instruction that was being executed, possibly out-of-order, at or around the time that the Performance Monitor alert occurred. In certain scenario SDAR happen to contain the kernel address even for userspace only sampling. Add checks to prevent it. Signed-off-by: Madhavan Srinivasan Signed-off-by: Michael Ellerman --- arch/powerpc/perf/core-book3s.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 1e55ae2f2afd..a00b364fb9d7 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -198,6 +198,10 @@ static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp) if (!(mmcra & MMCRA_SAMPLE_ENABLE) || sdar_valid) *addrp = mfspr(SPRN_SDAR); + + if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN) && + is_kernel_addr(mfspr(SPRN_SDAR))) + *addrp = 0; } static bool regs_sihv(struct pt_regs *regs) -- 2.30.2