Since commit ce2e6db554fa ("brcmfmac: Add support for getting nvram
contents from EFI variables") we have a device driver accessing the
efivars api (since next-20181107). Several functions in efivars api
assume __efivars is set, ie. will be accessed after efivars_register()
has been called. However, following NULL pointer access was reported
calling efivar_entry_size() from the brcmfmac device driver.
[ 14.177769] Unable to handle kernel NULL pointer dereference at
virtual address 00000008
[ 14.197303] pgd = 60bfa5f1
[ 14.211842] [00000008] *pgd=00000000
[ 14.227373] Internal error: Oops: 5 [#1] SMP ARM
[ 14.244244] Modules linked in: brcmfmac sha256_generic sha256_arm snd cfg80211 brcmutil soundcore snd_soc_tegra30_ahub tegra_wdt
[ 14.269109] CPU: 1 PID: 114 Comm: kworker/1:2 Not tainted 4.20.0-rc1-next-20181107-gd881de3 #1
[ 14.269114] Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
[ 14.269154] Workqueue: events request_firmware_work_func
[ 14.269177] PC is at efivar_entry_size+0x28/0x90
[ 14.269362] LR is at brcmf_fw_complete_request+0x3f8/0x8d4 [brcmfmac]
[ 14.269369] pc : [<c0c40718>] lr : [<bf2a3ef4>] psr: a00d0113
[ 14.269374] sp : ede7fe28 ip : ee983410 fp : c1787f30
[ 14.269378] r10: 00000000 r9 : 00000000 r8 : bf2b2258
[ 14.269384] r7 : ee983000 r6 : c1604c48 r5 : ede7fe88 r4 : edf337c0
[ 14.269389] r3 : 00000000 r2 : 00000000 r1 : ede7fe88 r0 : c17712c8
[ 14.269398] Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
[ 14.269404] Control: 10c5387d Table: ad16804a DAC: 00000051
Disassembly showed that the local static variable __efivars is NULL. Likely
because efivars_register() is not called on this Tegra platform. So adding
a NULL pointer check in efivar_entry_size() and similar functions while at
it. In efivars_register() a couple of sanity checks have been added.
Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
Reported-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Signed-off-by: Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx>
---
drivers/firmware/efi/vars.c | 108 +++++++++++++++++++++++++++++++++++---------
1 file changed, 87 insertions(+), 21 deletions(-)
diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c
index 9336ffd..5fbd8e7 100644
--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -318,7 +318,12 @@ struct variable_validate {
static efi_status_t
check_var_size(u32 attributes, unsigned long size)
{
- const struct efivar_operations *fops = __efivars->ops;
+ const struct efivar_operations *fops;
+
+ if (!__efivars)
+ return EFI_UNSUPPORTED;
+
+ fops = __efivars->ops;
if (!fops->query_variable_store)
return EFI_UNSUPPORTED;
@@ -329,7 +334,12 @@ struct variable_validate {
static efi_status_t
check_var_size_nonblocking(u32 attributes, unsigned long size)
{
- const struct efivar_operations *fops = __efivars->ops;
+ const struct efivar_operations *fops;
+
+ if (!__efivars)
+ return EFI_UNSUPPORTED;
+
+ fops = __efivars->ops;
if (!fops->query_variable_store)
return EFI_UNSUPPORTED;
@@ -429,13 +439,18 @@ static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
void *data, bool duplicates, struct list_head *head)
{
- const struct efivar_operations *ops = __efivars->ops;
+ const struct efivar_operations *ops;
unsigned long variable_name_size = 1024;
efi_char16_t *variable_name;
efi_status_t status;
efi_guid_t vendor_guid;
int err = 0;
+ if (!__efivars)
+ return -EFAULT;
+
+ ops = __efivars->ops;
+
variable_name = kzalloc(variable_name_size, GFP_KERNEL);
if (!variable_name) {
printk(KERN_ERR "efivars: Memory allocation failed.\n");
@@ -583,12 +598,14 @@ static void efivar_entry_list_del_unlock(struct efivar_entry *entry)
*/
int __efivar_entry_delete(struct efivar_entry *entry)
{
- const struct efivar_operations *ops = __efivars->ops;
efi_status_t status;
- status = ops->set_variable(entry->var.VariableName,
- &entry->var.VendorGuid,
- 0, 0, NULL);
+ if (!__efivars)
+ return -EINVAL;
+
+ status = __efivars->ops->set_variable(entry->var.VariableName,
+ &entry->var.VendorGuid,
+ 0, 0, NULL);
return efi_status_to_err(status);
}
@@ -607,12 +624,17 @@ int __efivar_entry_delete(struct efivar_entry *entry)
*/
int efivar_entry_delete(struct efivar_entry *entry)
{
- const struct efivar_operations *ops = __efivars->ops;
+ const struct efivar_operations *ops;
efi_status_t status;
if (down_interruptible(&efivars_lock))
return -EINTR;
+ if (!__efivars) {
+ up(&efivars_lock);
+ return -EINVAL;
+ }
+ ops = __efivars->ops;
status = ops->set_variable(entry->var.VariableName,
&entry->var.VendorGuid,
0, 0, NULL);
@@ -650,13 +672,19 @@ int efivar_entry_delete(struct efivar_entry *entry)
int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
unsigned long size, void *data, struct list_head *head)
{
- const struct efivar_operations *ops = __efivars->ops;
+ const struct efivar_operations *ops;
efi_status_t status;
efi_char16_t *name = entry->var.VariableName;
efi_guid_t vendor = entry->var.VendorGuid;
if (down_interruptible(&efivars_lock))
return -EINTR;
+
+ if (!__efivars) {
+ up(&efivars_lock);
+ return -EINVAL;
+ }
+ ops = __efivars->ops;
if (head && efivar_entry_find(name, vendor, head, false)) {
up(&efivars_lock);
return -EEXIST;
@@ -687,12 +715,17 @@ int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
u32 attributes, unsigned long size, void *data)
{
- const struct efivar_operations *ops = __efivars->ops;
+ const struct efivar_operations *ops;
efi_status_t status;
if (down_trylock(&efivars_lock))
return -EBUSY;
+ if (!__efivars) {
+ up(&efivars_lock);
+ return -EINVAL;
+ }
+
status = check_var_size_nonblocking(attributes,
size + ucs2_strsize(name, 1024));
if (status != EFI_SUCCESS) {
@@ -700,6 +733,7 @@ int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
return -ENOSPC;
}
+ ops = __efivars->ops;
status = ops->set_variable_nonblocking(name, &vendor, attributes,
size, data);
@@ -727,9 +761,13 @@ int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes,
bool block, unsigned long size, void *data)
{
- const struct efivar_operations *ops = __efivars->ops;
+ const struct efivar_operations *ops;
efi_status_t status;
+ if (!__efivars)
+ return -EINVAL;
+
+ ops = __efivars->ops;
if (!ops->query_variable_store)
return -ENOSYS;
@@ -829,13 +867,18 @@ struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid,
*/
int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
{
- const struct efivar_operations *ops = __efivars->ops;
+ const struct efivar_operations *ops;
efi_status_t status;
*size = 0;
if (down_interruptible(&efivars_lock))
return -EINTR;
+ if (!__efivars) {
+ up(&efivars_lock);
+ return -EINVAL;
+ }
+ ops = __efivars->ops;
status = ops->get_variable(entry->var.VariableName,
&entry->var.VendorGuid, NULL, size, NULL);
up(&efivars_lock);
@@ -861,12 +904,14 @@ int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
unsigned long *size, void *data)
{
- const struct efivar_operations *ops = __efivars->ops;
efi_status_t status;
- status = ops->get_variable(entry->var.VariableName,
- &entry->var.VendorGuid,
- attributes, size, data);
+ if (!__efivars)
+ return -EINVAL;
+
+ status = __efivars->ops->get_variable(entry->var.VariableName,
+ &entry->var.VendorGuid,
+ attributes, size, data);
return efi_status_to_err(status);
}
@@ -882,14 +927,19 @@ int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
unsigned long *size, void *data)
{
- const struct efivar_operations *ops = __efivars->ops;
efi_status_t status;
if (down_interruptible(&efivars_lock))
return -EINTR;
- status = ops->get_variable(entry->var.VariableName,
- &entry->var.VendorGuid,
- attributes, size, data);
+
+ if (!__efivars) {
+ up(&efivars_lock);
+ return -EINVAL;
+ }
+
+ status = __efivars->ops->get_variable(entry->var.VariableName,
+ &entry->var.VendorGuid,
+ attributes, size, data);
up(&efivars_lock);
return efi_status_to_err(status);
@@ -921,7 +971,7 @@ int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
unsigned long *size, void *data, bool *set)
{
- const struct efivar_operations *ops = __efivars->ops;
+ const struct efivar_operations *ops;
efi_char16_t *name = entry->var.VariableName;
efi_guid_t *vendor = &entry->var.VendorGuid;
efi_status_t status;
@@ -940,6 +990,11 @@ int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
if (down_interruptible(&efivars_lock))
return -EINTR;
+ if (!__efivars) {
+ err = -EINVAL;
+ goto out;
+ }
+
/*
* Ensure that the available space hasn't shrunk below the safe level
*/
@@ -956,6 +1011,8 @@ int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
}
}
+ ops = __efivars->ops;
+
status = ops->set_variable(name, vendor, attributes, *size, data);
if (status != EFI_SUCCESS) {
err = efi_status_to_err(status);
@@ -1138,6 +1195,15 @@ int efivars_register(struct efivars *efivars,
if (down_interruptible(&efivars_lock))
return -EINTR;
+ if (WARN(!efivars || !ops, "Invalid parameters\n"))
+ return -EINVAL;
+
+ /* check mandatory efivars operations */
+ if (WARN_ON(!ops->get_variable) ||
+ WARN_ON(!ops->set_variable) ||
+ WARN_ON(!ops->get_next_variable))
+ return -EINVAL;
+
efivars->ops = ops;
efivars->kobject = kobject;
--
1.9.1
