From 6ae285d5333a9c5ebf2a448a73065730b24481f9 Mon Sep 17 00:00:00 2001 From: Ido Yariv Date: Sat, 14 Apr 2012 23:20:30 +0300 Subject: [PATCH] arm: vfp: Fix memory corruption on PM suspend Commit 36af2a47 ("ARM: vfp: Always save VFP state in vfp_pm_suspend") introduced a potential use-after-free bug. On SMP systems, vfp_current_hw_state might hold dangling pointers in case a task which used the VFP last migrates to another CPU and then exits. If vfp_pm_suspend is called while vfp_current_hw_state still holds a pointer to the freed thread_info, that memory location will be written, potentially overwriting a new object allocated there. The original problem is only relevant to UP systems in which the VFP state is stored lazily. Fix this by only storing the VFP state on UP systems, and avoid doing so on SMP ones. Change-Id: I8f7026eb735b340fcef4cf12fbd12b9a0ea08d3f Signed-off-by: Ido Yariv Signed-off-by: Eyal Shapira Signed-off-by: Colin Cross --- arch/arm/vfp/vfpmodule.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index 53cb06fc3165..f1869138e9f5 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -419,9 +419,11 @@ static int vfp_pm_suspend(void) /* disable, just in case */ fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); } else if (vfp_current_hw_state[ti->cpu]) { +#ifndef CONFIG_SMP fmxr(FPEXC, fpexc | FPEXC_EN); vfp_save_state(vfp_current_hw_state[ti->cpu], fpexc); fmxr(FPEXC, fpexc); +#endif } /* clear any information we had about last context state */ -- 2.34.1