Commit f3d83e24 authored by Costantino Leandro's avatar Costantino Leandro Committed by Linus Torvalds

wmi: fix kernel panic when stack protection enabled.

Kernel panic arise when stack protection is enabled, since strncat will
add a null terminating byte '\0'; So in functions
like this one (wmi_query_block):
        char wc[4]="WC";
	strncat(method, block->object_id, 2);
the length of wc should be n+1 (wc[5]) or stack protection
fault will arise. This is not noticeable when stack protection is
disabled,but , isn't good either.

Panic Trace
       .... stack-protector: kernel stack corrupted in : fa7b182c
           [<c04a6c40>] ? panic+0x45/0xd9
	   [<c012925d>] ? __stack_chk_fail+0x1c/0x40
	   [<fa7b182c>] ? wmi_query_block+0x15a/0x162 [wmi]
	   [<fa7b182c>] ? wmi_query_block+0x15a/0x162 [wmi]
	   [<fa7e7000>] ? acer_wmi_init+0x00/0x61a [acer_wmi]
	   [<fa7e7135>] ? acer_wmi_init+0x135/0x61a [acer_wmi]
	   [<c0101159>] ? do_one_initcall+0x50+0x126

Addresses default avatarCostantino Leandro <>
Signed-off-by: default avatarCarlos Corbacho <>
Cc: Len Brown <>
Cc: Bjorn Helgaas <>
Cc: "Rafael J. Wysocki" <>
Cc: <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent ce8442b5
......@@ -270,7 +270,7 @@ u32 method_id, const struct acpi_buffer *in, struct acpi_buffer *out)
acpi_status status;
struct acpi_object_list input;
union acpi_object params[3];
char method[4] = "WM";
char method[5] = "WM";
if (!find_guid(guid_string, &wblock))
return AE_ERROR;
......@@ -328,8 +328,8 @@ struct acpi_buffer *out)
acpi_status status, wc_status = AE_ERROR;
struct acpi_object_list input, wc_input;
union acpi_object wc_params[1], wq_params[1];
char method[4];
char wc_method[4] = "WC";
char method[5];
char wc_method[5] = "WC";
if (!guid_string || !out)
......@@ -410,7 +410,7 @@ const struct acpi_buffer *in)
acpi_handle handle;
struct acpi_object_list input;
union acpi_object params[2];
char method[4] = "WS";
char method[5] = "WS";
if (!guid_string || !in)
return AE_BAD_DATA;
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