From: Dexuan Cui decui@microsoft.com
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
--- drivers/acpi/internal.h | 2 +- drivers/acpi/scan.c | 15 ++++++++++++++- 2 files changed, 15 insertions(+), 2 deletions(-)
--- a/drivers/acpi/internal.h +++ b/drivers/acpi/internal.h @@ -97,7 +97,7 @@ void acpi_scan_table_handler(u32 event, 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; }; --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -487,6 +487,7 @@ static void acpi_device_del(struct acpi_ 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; @@ -675,7 +676,14 @@ int acpi_device_add(struct acpi_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); } @@ -710,6 +718,11 @@ int acpi_device_add(struct acpi_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: