[patch V2 07/52] x86/fpu: Limit xstate copy size in xstateregs_set()

Thomas Gleixner
2021-06-14T16:38:13Z

If the count argument is larger than the xstate size, this will happily
copy beyond the end of xstate.

Fixes: 91c3dba7dbc1 ("x86/fpu/xstate: Fix PTRACE frames for XSAVES")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/fpu/regset.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -117,7 +117,7 @@ int xstateregs_set(struct task_struct *t
/*
* A whole standard-format XSAVE buffer is needed:
*/
- if ((pos != 0) || (count < fpu_user_xstate_size))
+ if (pos != 0 || count != fpu_user_xstate_size)
return -EFAULT;

xsave = &fpu->state.xsave;