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-rw-r--r--drivers/acpi/proc.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/acpi/proc.c b/drivers/acpi/proc.c
index d0d550d22a6d..f8b6f555ba52 100644
--- a/drivers/acpi/proc.c
+++ b/drivers/acpi/proc.c
@@ -398,6 +398,8 @@ acpi_system_write_wakeup_device(struct file *file,
if (len > 4)
len = 4;
+ if (len < 0)
+ return -EFAULT;
if (copy_from_user(strbuf, buffer, len))
return -EFAULT;