[PATCH 5.10 170/243] x86/fpu: Limit xstate copy size in xstateregs_set()

Greg Kroah-Hartman
2021-07-19T17:22:42Z

From: Thomas Gleixner <tglx@linutronix.de>

[ Upstream commit 07d6688b22e09be465652cf2da0da6bf86154df6 ]

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>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.120741557@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kernel/fpu/regset.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index c413756ba89f..6bb874441de8 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -117,7 +117,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
/*
* 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;
--
2.30.2