CVE-2024-56687
usb: musb: Fix hardware lockup on first Rx endpoint request
Published Dec 28, 2024
CVSS 3.1 · 5.5 Medium
EPSS < 1%
KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:
usb: musb: Fix hardware lockup on first Rx endpoint request
There is a possibility that a request's callback could be invoked from
usb_ep_queue() (call trace below, supplemented with missing calls):
req->complete from usb_gadget_giveback_request
(drivers/usb/gadget/udc/core.c:999)
usb_gadget_giveback_request from musb_g_giveback
(drivers/usb/musb/musb_gadget.c:147)
musb_g_giveback from rxstate
(drivers/usb/musb/musb_gadget.c:784)
rxstate from musb_ep_restart
(drivers/usb/musb/musb_gadget.c:1169)
musb_ep_restart from musb_ep_restart_resume_work
(drivers/usb/musb/musb_gadget.c:1176)
musb_ep_restart_resume_work from musb_queue_resume_work
(drivers/usb/musb/musb_core.c:2279)
musb_queue_resume_work from musb_gadget_queue
(drivers/usb/musb/musb_gadget.c:1241)
musb_gadget_queue from usb_ep_queue
(drivers/usb/gadget/udc/core.c:300)
According to the docstring of usb_ep_queue(), this should not happen:
"Note that @req's ->complete() callback must never be called from within
usb_ep_queue() as that can create deadlock situations."
In fact, a hardware lockup might occur in the following sequence:
1. The gadget is initialized using musb_gadget_enable().
2. Meanwhile, a packet arrives, and the RXPKTRDY flag is set, raising an
interrupt.
3. If IRQs are enabled, the interrupt is handled, but musb_g_rx() finds an
empty queue (next_request() returns NULL). The interrupt flag has
already been cleared by the glue layer handler, but the RXPKTRDY flag
remains set.
4. The first request is enqueued using usb_ep_queue(), leading to the call
of req->complete(), as shown in the call trace above.
5. If the callback enables IRQs and another packet is waiting, step (3)
repeats. The request queue is empty because usb_g_giveback() removes the
request before invoking the callback.
6. The endpoint remains locked up, as the interrupt triggered by hardware
setting the RXPKTRDY flag has been handled, but the flag itself remains
set.
For this scenario to occur, it is only necessary for IRQs to be enabled at
some point during the complete callback. This happens with the USB Ethernet
gadget, whose rx_complete() callback calls netif_rx(). If called in the
task context, netif_rx() disables the bottom halves (BHs). When the BHs are
re-enabled, IRQs are also enabled to allow soft IRQs to be processed. The
gadget itself is initialized at module load (or at boot if built-in), but
the first request is enqueued when the network interface is brought up,
triggering rx_complete() in the task context via ioctl(). If a packet
arrives while the interface is down, it can prevent the interface from
receiving any further packets from the USB host.
The situation is quite complicated with many parties involved. This
particular issue can be resolved in several possible ways:
1. Ensure that callbacks never enable IRQs. This would be difficult to
enforce, as discovering how netif_rx() interacts with interrupts was
already quite challenging and u_ether is not the only function driver.
Similar "bugs" could be hidden in other drivers as well.
2. Disable MUSB interrupts in musb_g_giveback() before calling the callback
and re-enable them afterwars (by calling musb_{dis,en}able_interrupts(),
for example). This would ensure that MUSB interrupts are not handled
during the callback, even if IRQs are enabled. In fact, it would allow
IRQs to be enabled when releasing the lock. However, this feels like an
inelegant hack.
3. Modify the interrupt handler to clear the RXPKTRDY flag if the request
queue is empty. While this approach also feels like a hack, it wastes
CPU time by attempting to handle incoming packets when the software is
not ready to process them.
4. Flush the Rx FIFO instead of calling rxstate() in musb_ep_restart().
This ensures that the hardware can receive packets when there is at
least one request in the queue. Once I
---truncated---
usb: musb: Fix hardware lockup on first Rx endpoint request
There is a possibility that a request's callback could be invoked from
usb_ep_queue() (call trace below, supplemented with missing calls):
req->complete from usb_gadget_giveback_request
(drivers/usb/gadget/udc/core.c:999)
usb_gadget_giveback_request from musb_g_giveback
(drivers/usb/musb/musb_gadget.c:147)
musb_g_giveback from rxstate
(drivers/usb/musb/musb_gadget.c:784)
rxstate from musb_ep_restart
(drivers/usb/musb/musb_gadget.c:1169)
musb_ep_restart from musb_ep_restart_resume_work
(drivers/usb/musb/musb_gadget.c:1176)
musb_ep_restart_resume_work from musb_queue_resume_work
(drivers/usb/musb/musb_core.c:2279)
musb_queue_resume_work from musb_gadget_queue
(drivers/usb/musb/musb_gadget.c:1241)
musb_gadget_queue from usb_ep_queue
(drivers/usb/gadget/udc/core.c:300)
According to the docstring of usb_ep_queue(), this should not happen:
"Note that @req's ->complete() callback must never be called from within
usb_ep_queue() as that can create deadlock situations."
In fact, a hardware lockup might occur in the following sequence:
1. The gadget is initialized using musb_gadget_enable().
2. Meanwhile, a packet arrives, and the RXPKTRDY flag is set, raising an
interrupt.
3. If IRQs are enabled, the interrupt is handled, but musb_g_rx() finds an
empty queue (next_request() returns NULL). The interrupt flag has
already been cleared by the glue layer handler, but the RXPKTRDY flag
remains set.
4. The first request is enqueued using usb_ep_queue(), leading to the call
of req->complete(), as shown in the call trace above.
5. If the callback enables IRQs and another packet is waiting, step (3)
repeats. The request queue is empty because usb_g_giveback() removes the
request before invoking the callback.
6. The endpoint remains locked up, as the interrupt triggered by hardware
setting the RXPKTRDY flag has been handled, but the flag itself remains
set.
For this scenario to occur, it is only necessary for IRQs to be enabled at
some point during the complete callback. This happens with the USB Ethernet
gadget, whose rx_complete() callback calls netif_rx(). If called in the
task context, netif_rx() disables the bottom halves (BHs). When the BHs are
re-enabled, IRQs are also enabled to allow soft IRQs to be processed. The
gadget itself is initialized at module load (or at boot if built-in), but
the first request is enqueued when the network interface is brought up,
triggering rx_complete() in the task context via ioctl(). If a packet
arrives while the interface is down, it can prevent the interface from
receiving any further packets from the USB host.
The situation is quite complicated with many parties involved. This
particular issue can be resolved in several possible ways:
1. Ensure that callbacks never enable IRQs. This would be difficult to
enforce, as discovering how netif_rx() interacts with interrupts was
already quite challenging and u_ether is not the only function driver.
Similar "bugs" could be hidden in other drivers as well.
2. Disable MUSB interrupts in musb_g_giveback() before calling the callback
and re-enable them afterwars (by calling musb_{dis,en}able_interrupts(),
for example). This would ensure that MUSB interrupts are not handled
during the callback, even if IRQs are enabled. In fact, it would allow
IRQs to be enabled when releasing the lock. However, this feels like an
inelegant hack.
3. Modify the interrupt handler to clear the RXPKTRDY flag if the request
queue is empty. While this approach also feels like a hack, it wastes
CPU time by attempting to handle incoming packets when the software is
not ready to process them.
4. Flush the Rx FIFO instead of calling rxstate() in musb_ep_restart().
This ensures that the hardware can receive packets when there is at
least one request in the queue. Once I
---truncated---
Affected Products
-
CVE record
-
NVD configurations
-
Red Hat packages
No data
-
OpenCVE enrichment
No data
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||||||||
| Linux | Linux | affected |
|
Configuration 1 [-]
|
No data.
No data available yet.
Remediation
Tracking
Advisories
| Source | ID | Title |
|---|---|---|
 Debian DLA |
DLA-4076-1 | linux-6.1 security update |
 EUVD |
EUVD-2024-53335 | In the Linux kernel, the following vulnerability has been resolved: usb: musb: Fix hardware lockup on first Rx endpoint request There is a possibility that a request's callback could be invoked from usb_ep_queue() (call trace below, supplemented with missing calls): req->complete from usb_gadget_giveback_request (drivers/usb/gadget/udc/core.c:999) usb_gadget_giveback_request from musb_g_giveback (drivers/usb/musb/musb_gadget.c:147) musb_g_giveback from rxstate (drivers/usb/musb/musb_gadget.c:784) rxstate from musb_ep_restart (drivers/usb/musb/musb_gadget.c:1169) musb_ep_restart from musb_ep_restart_resume_work (drivers/usb/musb/musb_gadget.c:1176) musb_ep_restart_resume_work from musb_queue_resume_work (drivers/usb/musb/musb_core.c:2279) musb_queue_resume_work from musb_gadget_queue (drivers/usb/musb/musb_gadget.c:1241) musb_gadget_queue from usb_ep_queue (drivers/usb/gadget/udc/core.c:300) According to the docstring of usb_ep_queue(), this should not happen: "Note that @req's ->complete() callback must never be called from within usb_ep_queue() as that can create deadlock situations." In fact, a hardware lockup might occur in the following sequence: 1. The gadget is initialized using musb_gadget_enable(). 2. Meanwhile, a packet arrives, and the RXPKTRDY flag is set, raising an interrupt. 3. If IRQs are enabled, the interrupt is handled, but musb_g_rx() finds an empty queue (next_request() returns NULL). The interrupt flag has already been cleared by the glue layer handler, but the RXPKTRDY flag remains set. 4. The first request is enqueued using usb_ep_queue(), leading to the call of req->complete(), as shown in the call trace above. 5. If the callback enables IRQs and another packet is waiting, step (3) repeats. The request queue is empty because usb_g_giveback() removes the request before invoking the callback. 6. The endpoint remains locked up, as the interrupt triggered by hardware setting the RXPKTRDY flag has been handled, but the flag itself remains set. For this scenario to occur, it is only necessary for IRQs to be enabled at some point during the complete callback. This happens with the USB Ethernet gadget, whose rx_complete() callback calls netif_rx(). If called in the task context, netif_rx() disables the bottom halves (BHs). When the BHs are re-enabled, IRQs are also enabled to allow soft IRQs to be processed. The gadget itself is initialized at module load (or at boot if built-in), but the first request is enqueued when the network interface is brought up, triggering rx_complete() in the task context via ioctl(). If a packet arrives while the interface is down, it can prevent the interface from receiving any further packets from the USB host. The situation is quite complicated with many parties involved. This particular issue can be resolved in several possible ways: 1. Ensure that callbacks never enable IRQs. This would be difficult to enforce, as discovering how netif_rx() interacts with interrupts was already quite challenging and u_ether is not the only function driver. Similar "bugs" could be hidden in other drivers as well. 2. Disable MUSB interrupts in musb_g_giveback() before calling the callback and re-enable them afterwars (by calling musb_{dis,en}able_interrupts(), for example). This would ensure that MUSB interrupts are not handled during the callback, even if IRQs are enabled. In fact, it would allow IRQs to be enabled when releasing the lock. However, this feels like an inelegant hack. 3. Modify the interrupt handler to clear the RXPKTRDY flag if the request queue is empty. While this approach also feels like a hack, it wastes CPU time by attempting to handle incoming packets when the software is not ready to process them. 4. Flush the Rx FIFO instead of calling rxstate() in musb_ep_restart(). This ensures that the hardware can receive packets when there is at least one request in the queue. Once I ---truncated--- |
 Ubuntu USN |
USN-7276-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-7277-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-7310-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-7449-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-7449-2 | Linux kernel (HWE) vulnerabilities |
| Ubuntu USN |
USN-7450-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-7451-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-7452-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-7453-1 | Linux kernel (Real-time) vulnerabilities |
| Ubuntu USN |
USN-7468-1 | Linux kernel (Azure, N-Series) vulnerabilities |
| Ubuntu USN |
USN-7523-1 | Linux kernel (Raspberry Pi Real-time) vulnerabilities |
| Ubuntu USN |
USN-7524-1 | Linux kernel (Raspberry Pi) vulnerabilities |
Metrics
No CVSS v4.0
Attack Vector Local
Attack Complexity Low
Privileges Required Low
Scope Unchanged
Confidentiality Impact None
Integrity Impact None
Availability Impact High
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.163% probability within 30 days)
Exploitation none
Automatable no
Technical Impact partial
References
History
Nov 3, 2025 9:30 PM
Added references
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|---|---|---|
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Oct 1, 2025 9:15 PM
Scoring metrics updated
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ssvc
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Feb 13, 2025 12:30 AM
Scoring metrics updated
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threat_severity
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threat_severity
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Jan 31, 2025 4:15 PM
First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Weaknesses | CWE-667 | |
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
Dec 30, 2024 1:30 AM
Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Dec 28, 2024 10:00 AM
Description updated. Title updated. Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: usb: musb: Fix hardware lockup on first Rx endpoint request There is a possibility that a request's callback could be invoked from usb_ep_queue() (call trace below, supplemented with missing calls): req->complete from usb_gadget_giveback_request (drivers/usb/gadget/udc/core.c:999) usb_gadget_giveback_request from musb_g_giveback (drivers/usb/musb/musb_gadget.c:147) musb_g_giveback from rxstate (drivers/usb/musb/musb_gadget.c:784) rxstate from musb_ep_restart (drivers/usb/musb/musb_gadget.c:1169) musb_ep_restart from musb_ep_restart_resume_work (drivers/usb/musb/musb_gadget.c:1176) musb_ep_restart_resume_work from musb_queue_resume_work (drivers/usb/musb/musb_core.c:2279) musb_queue_resume_work from musb_gadget_queue (drivers/usb/musb/musb_gadget.c:1241) musb_gadget_queue from usb_ep_queue (drivers/usb/gadget/udc/core.c:300) According to the docstring of usb_ep_queue(), this should not happen: "Note that @req's ->complete() callback must never be called from within usb_ep_queue() as that can create deadlock situations." In fact, a hardware lockup might occur in the following sequence: 1. The gadget is initialized using musb_gadget_enable(). 2. Meanwhile, a packet arrives, and the RXPKTRDY flag is set, raising an interrupt. 3. If IRQs are enabled, the interrupt is handled, but musb_g_rx() finds an empty queue (next_request() returns NULL). The interrupt flag has already been cleared by the glue layer handler, but the RXPKTRDY flag remains set. 4. The first request is enqueued using usb_ep_queue(), leading to the call of req->complete(), as shown in the call trace above. 5. If the callback enables IRQs and another packet is waiting, step (3) repeats. The request queue is empty because usb_g_giveback() removes the request before invoking the callback. 6. The endpoint remains locked up, as the interrupt triggered by hardware setting the RXPKTRDY flag has been handled, but the flag itself remains set. For this scenario to occur, it is only necessary for IRQs to be enabled at some point during the complete callback. This happens with the USB Ethernet gadget, whose rx_complete() callback calls netif_rx(). If called in the task context, netif_rx() disables the bottom halves (BHs). When the BHs are re-enabled, IRQs are also enabled to allow soft IRQs to be processed. The gadget itself is initialized at module load (or at boot if built-in), but the first request is enqueued when the network interface is brought up, triggering rx_complete() in the task context via ioctl(). If a packet arrives while the interface is down, it can prevent the interface from receiving any further packets from the USB host. The situation is quite complicated with many parties involved. This particular issue can be resolved in several possible ways: 1. Ensure that callbacks never enable IRQs. This would be difficult to enforce, as discovering how netif_rx() interacts with interrupts was already quite challenging and u_ether is not the only function driver. Similar "bugs" could be hidden in other drivers as well. 2. Disable MUSB interrupts in musb_g_giveback() before calling the callback and re-enable them afterwars (by calling musb_{dis,en}able_interrupts(), for example). This would ensure that MUSB interrupts are not handled during the callback, even if IRQs are enabled. In fact, it would allow IRQs to be enabled when releasing the lock. However, this feels like an inelegant hack. 3. Modify the interrupt handler to clear the RXPKTRDY flag if the request queue is empty. While this approach also feels like a hack, it wastes CPU time by attempting to handle incoming packets when the software is not ready to process them. 4. Flush the Rx FIFO instead of calling rxstate() in musb_ep_restart(). This ensures that the hardware can receive packets when there is at least one request in the queue. Once I ---truncated--- | |
| Title | usb: musb: Fix hardware lockup on first Rx endpoint request | |
| References |
|
|
Subscriptions
Weaknesses
