x86/fpu: Use validate_xstate_header() to validate the xstate_header in copy_user_to_x...

Tighten the checks in copy_user_to_xstate().

Signed-off-by: Eric Biggers <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kevin Hao <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Michael Halcrow <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Wanpeng Li <[email protected]>
Cc: Yu-cheng Yu <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index b6d78b78b5c2b4df021b6917056d966b0f88819e..f1d5476c902209eebeae83d3cd30fe5b6226921c 100644 (file)
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1188,16 +1188,15 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 }
 
 /*
- * Convert from a ptrace standard-format user-space buffer to kernel XSAVES format
- * and copy to the target thread. This is called from xstateregs_set() and
- * there we check the CPU has XSAVES and a whole standard-sized buffer
- * exists.
+ * Convert from a ptrace or sigreturn standard-format user-space buffer to
+ * kernel XSAVES format and copy to the target thread. This is called from
+ * xstateregs_set(), as well as potentially from the sigreturn() and
+ * rt_sigreturn() system calls.
  */
 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
 {
        unsigned int offset, size;
        int i;
-       u64 allowed_features;
        struct xstate_header hdr;
 
        offset = offsetof(struct xregs_state, header);
@@ -1206,12 +1205,7 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
        if (__copy_from_user(&hdr, ubuf + offset, size))
                return -EFAULT;
 
-       /*
-        * Reject if the user sets any disabled or supervisor features:
-        */
-       allowed_features = xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR;
-
-       if (hdr.xfeatures & ~allowed_features)
+       if (validate_xstate_header(&hdr))
                return -EINVAL;
 
        for (i = 0; i < XFEATURE_MAX; i++) {