dell-wmi: Clean up hotkey table size check

[deliverable/linux.git] / drivers / platform / x86 / dell-wmi.c

diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
index d6ae69e0a787d85d8c63635f9fc670fc92658460..32808a46332539191c6456dbc6c7016628c91220 100644 (file)
--- a/drivers/platform/x86/dell-wmi.c
+++ b/drivers/platform/x86/dell-wmi.c
@@ -351,13 +351,24 @@ static void __init handle_dmi_entry(const struct dmi_header *dm,
        if (results->err || results->keymap)
                return;         /* We already found the hotkey table. */
 
-       if (dm->type != 0xb2 || dm->length <= 6)
+       if (dm->type != 0xb2)
                return;
 
        table = container_of(dm, struct dell_bios_hotkey_table, header);
 
-       hotkey_num = (table->header.length - 4) /
+       hotkey_num = (table->header.length -
+                     sizeof(struct dell_bios_hotkey_table)) /
                                sizeof(struct dell_bios_keymap_entry);
+       if (hotkey_num < 1) {
+               /*
+                * Historically, dell-wmi would ignore a DMI entry of
+                * fewer than 7 bytes.  Sizes between 4 and 8 bytes are
+                * nonsensical (both the header and all entries are 4
+                * bytes), so we approximate the old behavior by
+                * ignoring tables with fewer than one entry.
+                */
+               return;
+       }
 
        keymap = kcalloc(hotkey_num + 1, sizeof(struct key_entry), GFP_KERNEL);
        if (!keymap) {