From 1773543ea9bac92670a2e84ced14839c8f8a8399 Mon Sep 17 00:00:00 2001 From: Arend van Spriel Date: Thu, 29 Nov 2018 18:12:27 +0100 Subject: firmware/efi: Add NULL pointer checks in efivars API functions [ Upstream commit ab2180a15ce54739fed381efb4cb12e78dfb1561 ] Since commit: ce2e6db554fa ("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 : [] lr : [] 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 Signed-off-by: Arend van Spriel Signed-off-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Bhupesh Sharma Cc: Borislav Petkov Cc: Dave Hansen Cc: Eric Snowberg Cc: Hans de Goede Cc: Joe Perches Cc: Julien Thierry Cc: Linus Torvalds Cc: Marc Zyngier Cc: Matt Fleming Cc: Nathan Chancellor Cc: Peter Zijlstra Cc: Sai Praneeth Prakhya Cc: Sedat Dilek Cc: Thomas Gleixner Cc: YiFei Zhu Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20181129171230.18699-9-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- drivers/firmware/efi/vars.c | 99 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 78 insertions(+), 21 deletions(-) (limited to 'drivers/firmware/efi/vars.c') diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c index 9336ffdf6e2c..fceaafd67ec6 100644 --- a/drivers/firmware/efi/vars.c +++ b/drivers/firmware/efi/vars.c @@ -318,7 +318,12 @@ EXPORT_SYMBOL_GPL(efivar_variable_is_removable); 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 @@ check_var_size(u32 attributes, unsigned long size) 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 @@ EXPORT_SYMBOL_GPL(__efivar_entry_delete); */ 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 @@ EXPORT_SYMBOL_GPL(efivar_entry_delete); 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 @@ static int 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 @@ efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor, return -ENOSPC; } + ops = __efivars->ops; status = ops->set_variable_nonblocking(name, &vendor, attributes, size, data); @@ -727,9 +761,13 @@ efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor, 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 @@ EXPORT_SYMBOL_GPL(efivar_entry_find); */ 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 @@ EXPORT_SYMBOL_GPL(efivar_entry_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 @@ EXPORT_SYMBOL_GPL(__efivar_entry_get); 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 @@ EXPORT_SYMBOL_GPL(efivar_entry_get); 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); -- cgit v1.2.3