x86/fpu: Fix __user annotations

In save_xstate_epilog(), use __user when type-casting userspace
pointers.

In setup_sigcontext() and x32_setup_rt_frame(), cast the userspace
pointers to 'unsigned long __user *' before writing into them. These
pointers are originally '__u32 __user *' or '__u64 __user *', causing
sparse to complain when a userspace pointer is written into them. The
casts are okay because the pointers always point to pointer-sized
values.

Thanks to Luc Van Oostenryck and Al Viro for explaining this to me.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mukesh Ojha <mojha@codeaurora.org>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190329214652.258477-3-jannh@google.com

diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index f6a1d299627c5825adb8214afe18731a3d39a53e..55b80de13ea5a2c0d9e8accb3c999079a2ba1bcd 100644 (file)
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -92,13 +92,13 @@ static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
                return err;
 
        err |= __put_user(FP_XSTATE_MAGIC2,
-                         (__u32 *)(buf + fpu_user_xstate_size));
+                         (__u32 __user *)(buf + fpu_user_xstate_size));
 
        /*
         * Read the xfeatures which we copied (directly from the cpu or
         * from the state in task struct) to the user buffers.
         */
-       err |= __get_user(xfeatures, (__u32 *)&x->header.xfeatures);
+       err |= __get_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
 
        /*
         * For legacy compatible, we always set FP/SSE bits in the bit
@@ -113,7 +113,7 @@ static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
         */
        xfeatures |= XFEATURE_MASK_FPSSE;
 
-       err |= __put_user(xfeatures, (__u32 *)&x->header.xfeatures);
+       err |= __put_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
 
        return err;
 }

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 08dfd4c1a4f95a19c78c855028e95b6be01ba02b..b419e1a1a0ce71f2cdca9891bd8cecd4d322a21b 100644 (file)
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -206,7 +206,7 @@ int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
                put_user_ex(regs->ss, &sc->ss);
 #endif /* CONFIG_X86_32 */
 
-               put_user_ex(fpstate, &sc->fpstate);
+               put_user_ex(fpstate, (unsigned long __user *)&sc->fpstate);
 
                /* non-iBCS2 extensions.. */
                put_user_ex(mask, &sc->oldmask);
@@ -569,7 +569,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig,
                        restorer = NULL;
                        err |= -EFAULT;
                }
-               put_user_ex(restorer, &frame->pretcode);
+               put_user_ex(restorer, (unsigned long __user *)&frame->pretcode);
        } put_user_catch(err);
 
        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,