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")
It looks like so far an ID string of >=15 chars is only seen in the guest
BIOS/firmware by Hyper-V, and AFAIK the ID string "HYPER_V_GEN_COUNTER_V1"
is never used by Linux VM on Hyper-V, so let's just truncate the string to
fix the panic.
Signed-off-by: Dexuan Cui <de...@microsoft.com>
---
drivers/acpi/scan.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index a1b226eb2ce2..b801442b6b1b 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -674,7 +674,8 @@ 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));
+ strlcpy(acpi_device_bus_id->bus_id, acpi_device_hid(device),
+ sizeof(acpi_device_bus_id->bus_id));
acpi_device_bus_id->instance_no = 0;
list_add_tail(&acpi_device_bus_id->node, &acpi_bus_id_list);
}
--
2.19.1
