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authorAndy Lutomirski <luto@kernel.org>2016-02-15 08:32:33 -0800
committerDarren Hart <dvhart@linux.intel.com>2016-03-23 10:05:44 -0700
commit18b6f80f5095036bd2204c54c89a5a0f5a785e3d (patch)
treede5e85f413d4c0a5eadf0dd9e2251abbd74c2b01 /drivers/platform
parent0c41a08e131d753af48ae6f052aed8d530b9c976 (diff)
downloadlinux-18b6f80f5095036bd2204c54c89a5a0f5a785e3d.tar.bz2
dell-wmi: Stop storing pointers to DMI tables
The dmi_walk function maps the DMI table, walks it, and unmaps it. This means that the dell_bios_hotkey_table that find_hk_type stores points to unmapped memory by the time it gets read. I've been able to trigger crashes caused by the stale pointer a couple of times, but never on a stock kernel. Fix it by generating the keymap in the dmi_walk callback instead of storing a pointer. Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Pali Rohár <pali.rohar@gmail.com> Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Diffstat (limited to 'drivers/platform')
-rw-r--r--drivers/platform/x86/dell-wmi.c74
1 files changed, 46 insertions, 28 deletions
diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
index 368e193c2741..d6ae69e0a787 100644
--- a/drivers/platform/x86/dell-wmi.c
+++ b/drivers/platform/x86/dell-wmi.c
@@ -120,7 +120,10 @@ struct dell_bios_hotkey_table {
};
-static const struct dell_bios_hotkey_table *dell_bios_hotkey_table;
+struct dell_dmi_results {
+ int err;
+ struct key_entry *keymap;
+};
/* Uninitialized entries here are KEY_RESERVED == 0. */
static const u16 bios_to_linux_keycode[256] __initconst = {
@@ -337,20 +340,34 @@ static void dell_wmi_notify(u32 value, void *context)
kfree(obj);
}
-static const struct key_entry * __init dell_wmi_prepare_new_keymap(void)
+static void __init handle_dmi_entry(const struct dmi_header *dm,
+ void *opaque)
{
- int hotkey_num = (dell_bios_hotkey_table->header.length - 4) /
- sizeof(struct dell_bios_keymap_entry);
+ struct dell_dmi_results *results = opaque;
+ struct dell_bios_hotkey_table *table;
struct key_entry *keymap;
- int i;
+ int hotkey_num, i;
+
+ if (results->err || results->keymap)
+ return; /* We already found the hotkey table. */
+
+ if (dm->type != 0xb2 || dm->length <= 6)
+ return;
+
+ table = container_of(dm, struct dell_bios_hotkey_table, header);
+
+ hotkey_num = (table->header.length - 4) /
+ sizeof(struct dell_bios_keymap_entry);
keymap = kcalloc(hotkey_num + 1, sizeof(struct key_entry), GFP_KERNEL);
- if (!keymap)
- return NULL;
+ if (!keymap) {
+ results->err = -ENOMEM;
+ return;
+ }
for (i = 0; i < hotkey_num; i++) {
const struct dell_bios_keymap_entry *bios_entry =
- &dell_bios_hotkey_table->keymap[i];
+ &table->keymap[i];
/* Uninitialized entries are 0 aka KEY_RESERVED. */
u16 keycode = (bios_entry->keycode <
@@ -379,11 +396,12 @@ static const struct key_entry * __init dell_wmi_prepare_new_keymap(void)
keymap[hotkey_num].type = KE_END;
- return keymap;
+ results->keymap = keymap;
}
static int __init dell_wmi_input_setup(void)
{
+ struct dell_dmi_results dmi_results = {};
int err;
dell_wmi_input_dev = input_allocate_device();
@@ -394,20 +412,31 @@ static int __init dell_wmi_input_setup(void)
dell_wmi_input_dev->phys = "wmi/input0";
dell_wmi_input_dev->id.bustype = BUS_HOST;
- if (dell_new_hk_type) {
- const struct key_entry *keymap = dell_wmi_prepare_new_keymap();
- if (!keymap) {
- err = -ENOMEM;
- goto err_free_dev;
- }
+ if (dmi_walk(handle_dmi_entry, &dmi_results)) {
+ /*
+ * Historically, dell-wmi ignored dmi_walk errors. A failure
+ * is certainly surprising, but it probably just indicates
+ * a very old laptop.
+ */
+ pr_warn("no DMI; using the old-style hotkey interface\n");
+ }
+
+ if (dmi_results.err) {
+ err = dmi_results.err;
+ goto err_free_dev;
+ }
+
+ if (dmi_results.keymap) {
+ dell_new_hk_type = true;
- err = sparse_keymap_setup(dell_wmi_input_dev, keymap, NULL);
+ err = sparse_keymap_setup(dell_wmi_input_dev,
+ dmi_results.keymap, NULL);
/*
* Sparse keymap library makes a copy of keymap so we
* don't need the original one that was allocated.
*/
- kfree(keymap);
+ kfree(dmi_results.keymap);
} else {
err = sparse_keymap_setup(dell_wmi_input_dev,
dell_wmi_legacy_keymap, NULL);
@@ -434,15 +463,6 @@ static void dell_wmi_input_destroy(void)
input_unregister_device(dell_wmi_input_dev);
}
-static void __init find_hk_type(const struct dmi_header *dm, void *dummy)
-{
- if (dm->type == 0xb2 && dm->length > 6) {
- dell_new_hk_type = true;
- dell_bios_hotkey_table =
- container_of(dm, struct dell_bios_hotkey_table, header);
- }
-}
-
/*
* Descriptor buffer is 128 byte long and contains:
*
@@ -524,8 +544,6 @@ static int __init dell_wmi_init(void)
if (err)
return err;
- dmi_walk(find_hk_type, NULL);
-
err = dell_wmi_input_setup();
if (err)
return err;