From b13de7019c1b67f0c1b987fc9fe82fcc371ba1d2 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Mon, 15 Feb 2016 08:32:35 -0800 Subject: [PATCH] dell-wmi: Clean up hotkey table size check MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Checking the table for a minimum size of 7 bytes makes no sense: any valid hotkey table has a size that's a multiple of 4. Clean this up: replace the hardcoded header length with a sizeof and change the check to ignore an empty hotkey table. The only behavior change is that a 7-byte table (which is nonsensical) will now be treated as absent instead of as valid but empty. Reported-by: Jean Delvare Signed-off-by: Andy Lutomirski Acked-by: Pali Rohár Signed-off-by: Darren Hart --- drivers/platform/x86/dell-wmi.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c index d6ae69e..32808a4 100644 --- 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) { -- 2.7.4