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.
Cc: sta...@vger.kernel.org
Signed-off-by: Andy Lutomirski <l...@kernel.org>
---
This seems to work on my laptop. It applies to platform-drivers-x86/for-next.
drivers/platform/x86/dell-wmi.c | 69 +++++++++++++++++++++++++----------------
1 file changed, 42 insertions(+), 27 deletions(-)
diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
index 57402c4c394e..52db2721d7e3 100644
--- a/drivers/platform/x86/dell-wmi.c
+++ b/drivers/platform/x86/dell-wmi.c
@@ -116,7 +116,10 @@ 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 = {
@@ -316,20 +319,34 @@ 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_table(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 <
@@ -358,11 +375,13 @@ static const struct key_entry * __init
dell_wmi_prepare_new_keymap(void)
keymap[hotkey_num].type = KE_END;
- return keymap;
+ results->err = 0;
+ 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();
@@ -373,20 +392,26 @@ 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;
- }
+ err = dmi_walk(handle_dmi_table, &dmi_results);
+ if (err)
+ goto err_free_dev;
- err = sparse_keymap_setup(dell_wmi_input_dev, keymap, NULL);
+ 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,
+ 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);
@@ -413,15 +438,6 @@ 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);
- }
-}
-
static int __init dell_wmi_init(void)
{
int err;
@@ -432,7 +448,6 @@ static int __init dell_wmi_init(void)
return -ENODEV;
}
- dmi_walk(find_hk_type, NULL);
acpi_video = acpi_video_get_backlight_type() != acpi_backlight_vendor;
err = dell_wmi_input_setup();
--
2.5.0
--
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