[patch V2 05/14] x86/fpu: Limit xstate copy size in xstateregs_set()

From: Thomas Gleixner
Date: Sat Jun 05 2021 - 20:32:40 EST


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@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
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;