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firmware/efi: Add NULL pointer checks in efivars API functions
Since commit:
ce2e6db554 ("brcmfmac: Add support for getting nvram contents from EFI variables")
we have a device driver accessing the efivars API. Several functions in
the efivars API assume __efivars is set, i.e., that they will be accessed
only after efivars_register() has been called. However, the following NULL
pointer access was reported calling efivar_entry_size() from the brcmfmac
device driver:
Unable to handle kernel NULL pointer dereference at virtual address 00000008
pgd = 60bfa5f1
[00000008] *pgd=00000000
Internal error: Oops: 5 [#1] SMP ARM
...
Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
Workqueue: events request_firmware_work_func
PC is at efivar_entry_size+0x28/0x90
LR is at brcmf_fw_complete_request+0x3f8/0x8d4 [brcmfmac]
pc : [<c0c40718>] lr : [<bf2a3ef4>] psr: a00d0113
sp : ede7fe28 ip : ee983410 fp : c1787f30
r10: 00000000 r9 : 00000000 r8 : bf2b2258
r7 : ee983000 r6 : c1604c48 r5 : ede7fe88 r4 : edf337c0
r3 : 00000000 r2 : 00000000 r1 : ede7fe88 r0 : c17712c8
Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: ad16804a DAC: 00000051
Disassembly showed that the local static variable __efivars is NULL,
which is not entirely unexpected given that it is a non-EFI platform.
So add a NULL pointer check to efivar_entry_size(), and to related
functions while at it. In efivars_register() a couple of sanity checks
are added as well.
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Eric Snowberg <eric.snowberg@oracle.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Julien Thierry <julien.thierry@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: YiFei Zhu <zhuyifei1999@gmail.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20181129171230.18699-9-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Arend van Spriel
Ingo Molnar
parent
79c2206d36
commit
ab2180a15c
@ -318,7 +318,12 @@ EXPORT_SYMBOL_GPL(efivar_variable_is_removable);
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static efi_status_t
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check_var_size(u32 attributes, unsigned long size)
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{
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const struct efivar_operations *fops = __efivars->ops;
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const struct efivar_operations *fops;
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if (!__efivars)
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return EFI_UNSUPPORTED;
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fops = __efivars->ops;
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if (!fops->query_variable_store)
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return EFI_UNSUPPORTED;
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@ -329,7 +334,12 @@ check_var_size(u32 attributes, unsigned long size)
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static efi_status_t
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check_var_size_nonblocking(u32 attributes, unsigned long size)
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{
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const struct efivar_operations *fops = __efivars->ops;
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const struct efivar_operations *fops;
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if (!__efivars)
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return EFI_UNSUPPORTED;
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fops = __efivars->ops;
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if (!fops->query_variable_store)
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return EFI_UNSUPPORTED;
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@ -429,13 +439,18 @@ static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
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int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
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void *data, bool duplicates, struct list_head *head)
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{
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const struct efivar_operations *ops = __efivars->ops;
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const struct efivar_operations *ops;
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unsigned long variable_name_size = 1024;
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efi_char16_t *variable_name;
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efi_status_t status;
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efi_guid_t vendor_guid;
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int err = 0;
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if (!__efivars)
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return -EFAULT;
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ops = __efivars->ops;
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variable_name = kzalloc(variable_name_size, GFP_KERNEL);
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if (!variable_name) {
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printk(KERN_ERR "efivars: Memory allocation failed.\n");
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@ -583,12 +598,14 @@ static void efivar_entry_list_del_unlock(struct efivar_entry *entry)
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*/
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int __efivar_entry_delete(struct efivar_entry *entry)
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{
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const struct efivar_operations *ops = __efivars->ops;
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efi_status_t status;
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status = ops->set_variable(entry->var.VariableName,
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&entry->var.VendorGuid,
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0, 0, NULL);
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if (!__efivars)
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return -EINVAL;
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status = __efivars->ops->set_variable(entry->var.VariableName,
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&entry->var.VendorGuid,
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0, 0, NULL);
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return efi_status_to_err(status);
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}
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@ -607,12 +624,17 @@ EXPORT_SYMBOL_GPL(__efivar_entry_delete);
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*/
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int efivar_entry_delete(struct efivar_entry *entry)
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{
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const struct efivar_operations *ops = __efivars->ops;
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const struct efivar_operations *ops;
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efi_status_t status;
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if (down_interruptible(&efivars_lock))
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return -EINTR;
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if (!__efivars) {
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up(&efivars_lock);
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return -EINVAL;
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}
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ops = __efivars->ops;
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status = ops->set_variable(entry->var.VariableName,
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&entry->var.VendorGuid,
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0, 0, NULL);
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@ -650,13 +672,19 @@ EXPORT_SYMBOL_GPL(efivar_entry_delete);
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int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
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unsigned long size, void *data, struct list_head *head)
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{
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const struct efivar_operations *ops = __efivars->ops;
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const struct efivar_operations *ops;
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efi_status_t status;
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efi_char16_t *name = entry->var.VariableName;
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efi_guid_t vendor = entry->var.VendorGuid;
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if (down_interruptible(&efivars_lock))
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return -EINTR;
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if (!__efivars) {
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up(&efivars_lock);
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return -EINVAL;
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}
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ops = __efivars->ops;
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if (head && efivar_entry_find(name, vendor, head, false)) {
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up(&efivars_lock);
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return -EEXIST;
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@ -687,12 +715,17 @@ static int
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efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
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u32 attributes, unsigned long size, void *data)
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{
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const struct efivar_operations *ops = __efivars->ops;
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const struct efivar_operations *ops;
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efi_status_t status;
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if (down_trylock(&efivars_lock))
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return -EBUSY;
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if (!__efivars) {
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up(&efivars_lock);
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return -EINVAL;
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}
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status = check_var_size_nonblocking(attributes,
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size + ucs2_strsize(name, 1024));
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if (status != EFI_SUCCESS) {
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@ -700,6 +733,7 @@ efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
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return -ENOSPC;
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}
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ops = __efivars->ops;
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status = ops->set_variable_nonblocking(name, &vendor, attributes,
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size, data);
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@ -727,9 +761,13 @@ efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
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int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes,
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bool block, unsigned long size, void *data)
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{
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const struct efivar_operations *ops = __efivars->ops;
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const struct efivar_operations *ops;
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efi_status_t status;
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if (!__efivars)
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return -EINVAL;
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ops = __efivars->ops;
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if (!ops->query_variable_store)
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return -ENOSYS;
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@ -829,13 +867,18 @@ EXPORT_SYMBOL_GPL(efivar_entry_find);
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*/
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int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
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{
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const struct efivar_operations *ops = __efivars->ops;
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const struct efivar_operations *ops;
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efi_status_t status;
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*size = 0;
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if (down_interruptible(&efivars_lock))
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return -EINTR;
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if (!__efivars) {
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up(&efivars_lock);
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return -EINVAL;
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}
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ops = __efivars->ops;
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status = ops->get_variable(entry->var.VariableName,
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&entry->var.VendorGuid, NULL, size, NULL);
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up(&efivars_lock);
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@ -861,12 +904,14 @@ EXPORT_SYMBOL_GPL(efivar_entry_size);
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int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
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unsigned long *size, void *data)
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{
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const struct efivar_operations *ops = __efivars->ops;
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efi_status_t status;
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status = ops->get_variable(entry->var.VariableName,
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&entry->var.VendorGuid,
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attributes, size, data);
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if (!__efivars)
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return -EINVAL;
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status = __efivars->ops->get_variable(entry->var.VariableName,
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&entry->var.VendorGuid,
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attributes, size, data);
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return efi_status_to_err(status);
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}
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@ -882,14 +927,19 @@ EXPORT_SYMBOL_GPL(__efivar_entry_get);
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int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
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unsigned long *size, void *data)
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{
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const struct efivar_operations *ops = __efivars->ops;
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efi_status_t status;
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if (down_interruptible(&efivars_lock))
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return -EINTR;
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status = ops->get_variable(entry->var.VariableName,
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&entry->var.VendorGuid,
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attributes, size, data);
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if (!__efivars) {
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up(&efivars_lock);
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return -EINVAL;
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}
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status = __efivars->ops->get_variable(entry->var.VariableName,
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&entry->var.VendorGuid,
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attributes, size, data);
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up(&efivars_lock);
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return efi_status_to_err(status);
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@ -921,7 +971,7 @@ EXPORT_SYMBOL_GPL(efivar_entry_get);
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int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
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unsigned long *size, void *data, bool *set)
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{
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const struct efivar_operations *ops = __efivars->ops;
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const struct efivar_operations *ops;
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efi_char16_t *name = entry->var.VariableName;
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efi_guid_t *vendor = &entry->var.VendorGuid;
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efi_status_t status;
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@ -940,6 +990,11 @@ int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
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if (down_interruptible(&efivars_lock))
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return -EINTR;
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if (!__efivars) {
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err = -EINVAL;
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goto out;
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}
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/*
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* Ensure that the available space hasn't shrunk below the safe level
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*/
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@ -956,6 +1011,8 @@ int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
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}
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}
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ops = __efivars->ops;
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status = ops->set_variable(name, vendor, attributes, *size, data);
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if (status != EFI_SUCCESS) {
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err = efi_status_to_err(status);
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