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authorDexuan Cui <decui@microsoft.com>2021-01-08 10:23:48 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-01-23 17:48:40 +0300
commit6f721258b94c6036b239415a99842477f8a6340c (patch)
treebcb6e15f510870bc2484b386d65f556ed92024e9 /drivers/acpi
parente8ffdaf20e6f6f0ce23d0afb35bc881de6d72452 (diff)
downloadlinux-6f721258b94c6036b239415a99842477f8a6340c.tar.xz
ACPI: scan: Harden acpi_device_add() against device ID overflows
commit a58015d638cd4e4555297b04bec9b49028369075 upstream. Linux VM on Hyper-V crashes with the latest mainline: [ 4.069624] detected buffer overflow in strcpy [ 4.077733] kernel BUG at lib/string.c:1149! .. [ 4.085819] RIP: 0010:fortify_panic+0xf/0x11 ... [ 4.085819] Call Trace: [ 4.085819] acpi_device_add.cold.15+0xf2/0xfb [ 4.085819] acpi_add_single_object+0x2a6/0x690 [ 4.085819] acpi_bus_check_add+0xc6/0x280 [ 4.085819] acpi_ns_walk_namespace+0xda/0x1aa [ 4.085819] acpi_walk_namespace+0x9a/0xc2 [ 4.085819] acpi_bus_scan+0x78/0x90 [ 4.085819] acpi_scan_init+0xfa/0x248 [ 4.085819] acpi_init+0x2c1/0x321 [ 4.085819] do_one_initcall+0x44/0x1d0 [ 4.085819] kernel_init_freeable+0x1ab/0x1f4 This is because of the recent buffer overflow detection in the commit 6a39e62abbaf ("lib: string.h: detect intra-object overflow in fortified string functions") Here acpi_device_bus_id->bus_id can only hold 14 characters, while the the acpi_device_hid(device) returns a 22-char string "HYPER_V_GEN_COUNTER_V1". Per ACPI Spec v6.2, Section 6.1.5 _HID (Hardware ID), if the ID is a string, it must be of the form AAA#### or NNNN####, i.e. 7 chars or 8 chars. The field bus_id in struct acpi_device_bus_id was originally defined as char bus_id[9], and later was enlarged to char bus_id[15] in 2007 in the commit bb0958544f3c ("ACPI: use more understandable bus_id for ACPI devices") Fix the issue by changing the field bus_id to const char *, and use kstrdup_const() to initialize it. Signed-off-by: Dexuan Cui <decui@microsoft.com> Tested-By: Jethro Beekman <jethro@fortanix.com> [ rjw: Subject change, whitespace adjustment ] Cc: All applicable <stable@vger.kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/internal.h2
-rw-r--r--drivers/acpi/scan.c15
2 files changed, 15 insertions, 2 deletions
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 2cd2ae152ab7..e6b10aad55d5 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -98,7 +98,7 @@ void acpi_scan_table_handler(u32 event, void *table, void *context);
extern struct list_head acpi_bus_id_list;
struct acpi_device_bus_id {
- char bus_id[15];
+ const char *bus_id;
unsigned int instance_no;
struct list_head node;
};
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 8bc1a778b3a4..e79db7ba2f10 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -485,6 +485,7 @@ static void acpi_device_del(struct acpi_device *device)
acpi_device_bus_id->instance_no--;
else {
list_del(&acpi_device_bus_id->node);
+ kfree_const(acpi_device_bus_id->bus_id);
kfree(acpi_device_bus_id);
}
break;
@@ -673,7 +674,14 @@ int acpi_device_add(struct acpi_device *device,
}
if (!found) {
acpi_device_bus_id = new_bus_id;
- strcpy(acpi_device_bus_id->bus_id, acpi_device_hid(device));
+ acpi_device_bus_id->bus_id =
+ kstrdup_const(acpi_device_hid(device), GFP_KERNEL);
+ if (!acpi_device_bus_id->bus_id) {
+ pr_err(PREFIX "Memory allocation error for bus id\n");
+ result = -ENOMEM;
+ goto err_free_new_bus_id;
+ }
+
acpi_device_bus_id->instance_no = 0;
list_add_tail(&acpi_device_bus_id->node, &acpi_bus_id_list);
}
@@ -708,6 +716,11 @@ int acpi_device_add(struct acpi_device *device,
if (device->parent)
list_del(&device->node);
list_del(&device->wakeup_list);
+
+ err_free_new_bus_id:
+ if (!found)
+ kfree(new_bus_id);
+
mutex_unlock(&acpi_device_lock);
err_detach: