In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_ncm: fix potential NULL ptr deref in ncm_bitrate()
In Google internal bug 265639009 we've received an (as yet) unreproducible
crash report from an aarch64 GKI 5.10.149-android13 running device.
AFAICT the source code is at:
https://android.googlesource.com/kernel/common/+/refs/tags/ASB-2022-12-05_13-5.10
The call stack is:
ncm_close() -> ncm_notify() -> ncm_do_notify()
with the crash at:
ncm_do_notify+0x98/0x270
Code: 79000d0b b9000a6c f940012a f9400269 (b9405d4b)
Which I believe disassembles to (I don't know ARM assembly, but it looks sane enough to me...):
// halfword (16-bit) store presumably to event->wLength (at offset 6 of struct usb_cdc_notification)
0B 0D 00 79 strh w11, [x8, #6]
// word (32-bit) store presumably to req->Length (at offset 8 of struct usb_request)
6C 0A 00 B9 str w12, [x19, #8]
// x10 (NULL) was read here from offset 0 of valid pointer x9
// IMHO we're reading 'cdev->gadget' and getting NULL
// gadget is indeed at offset 0 of struct usb_composite_dev
2A 01 40 F9 ldr x10, [x9]
// loading req->buf pointer, which is at offset 0 of struct usb_request
69 02 40 F9 ldr x9, [x19]
// x10 is null, crash, appears to be attempt to read cdev->gadget->max_speed
4B 5D 40 B9 ldr w11, [x10, #0x5c]
which seems to line up with ncm_do_notify() case NCM_NOTIFY_SPEED code fragment:
event->wLength = cpu_to_le16(8);
req->length = NCM_STATUS_BYTECOUNT;
/* SPEED_CHANGE data is up/down speeds in bits/sec */
data = req->buf + sizeof *event;
data[0] = cpu_to_le32(ncm_bitrate(cdev->gadget));
My analysis of registers and NULL ptr deref crash offset
(Unable to handle kernel NULL pointer dereference at virtual address 000000000000005c)
heavily suggests that the crash is due to 'cdev->gadget' being NULL when executing:
data[0] = cpu_to_le32(ncm_bitrate(cdev->gadget));
which calls:
ncm_bitrate(NULL)
which then calls:
gadget_is_superspeed(NULL)
which reads
((struct usb_gadget *)NULL)->max_speed
and hits a panic.
AFAICT, if I'm counting right, the offset of max_speed is indeed 0x5C.
(remember there's a GKI KABI reservation of 16 bytes in struct work_struct)
It's not at all clear to me how this is all supposed to work...
but returning 0 seems much better than panic-ing...
References
Configurations
Configuration 1 (hide)
|
History
11 Sep 2024, 16:27
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/09e4507ec8ef2d44da6ba4092b8ee2d81f216497 - Patch | |
| References | () https://git.kernel.org/stable/c/63d161f29cd39c050e8873aa36e0c9fc013bb763 - Patch | |
| References | () https://git.kernel.org/stable/c/a21da7f7aae618c785f7e4a275d43c06dc8412b6 - Patch | |
| References | () https://git.kernel.org/stable/c/a69c8dfb85b44be9cc223be07d35cc3a9baefbea - Patch | |
| References | () https://git.kernel.org/stable/c/c6ec929595c7443250b2a4faea988c62019d5cd2 - Patch | |
| References | () https://git.kernel.org/stable/c/e92c70059178da751e5af7de02384b7dfadb5ec7 - Patch | |
| References | () https://git.kernel.org/stable/c/fef6b29671b66dfb71f17e337c1ad14b5a2cedae - Patch | |
| First Time |
Linux linux Kernel
Linux |
|
| CWE | CWE-476 | |
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.5 |
| CPE | cpe:2.3:o:linux:linux_kernel:6.2:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.2:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.2:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.2:rc3:*:*:*:*:*:* |
21 Aug 2024, 12:30
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2024-08-21 07:15
Updated : 2024-09-11 16:27
NVD link : CVE-2023-52894
Mitre link : CVE-2023-52894
CVE.ORG link : CVE-2023-52894
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-476
NULL Pointer Dereference