CVE-2024-44951 (GCVE-0-2024-44951)
Vulnerability from cvelistv5
Published
2024-09-04 18:35
Modified
2026-08-05 11:37
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
serial: sc16is7xx: fix TX fifo corruption
Sometimes, when a packet is received on channel A at almost the same time
as a packet is about to be transmitted on channel B, we observe with a
logic analyzer that the received packet on channel A is transmitted on
channel B. In other words, the Tx buffer data on channel B is corrupted
with data from channel A.
The problem appeared since commit 4409df5866b7 ("serial: sc16is7xx: change
EFR lock to operate on each channels"), which changed the EFR locking to
operate on each channel instead of chip-wise.
This commit has introduced a regression, because the EFR lock is used not
only to protect the EFR registers access, but also, in a very obscure and
undocumented way, to protect access to the data buffer, which is shared by
the Tx and Rx handlers, but also by each channel of the IC.
Fix this regression first by switching to kfifo_out_linear_ptr() in
sc16is7xx_handle_tx() to eliminate the need for a shared Rx/Tx buffer.
Secondly, replace the chip-wise Rx buffer with a separate Rx buffer for
each channel.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 4409df5866b7ff7686ba27e449ca97a92ee063c9 Version: 4409df5866b7ff7686ba27e449ca97a92ee063c9 Version: 4b068e55bf5ea7bab4d8a282c6a24b03e80c0b68 Version: 9879e1bec3c0f077427dd0d258c80c63ce9babdf Version: dbe196ca489f3833e0f9eeb86ac346194f131c91 Version: 6.1.76 ≤ Version: 6.6.15 ≤ Version: 6.7.3 ≤ |
||
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"value": "AV:L - Both sides of the race are driven purely from local userspace \u2014 `write(2)` on one `/dev/ttySC*` node queues `tx_work` into the chip kworker while `read(2)`/incoming traffic on the sibling channel runs the threaded-IRQ RX handler. No network path exists, but no physical access is needed either, since the corrupting write and the observable leak both occur through tty device nodes.\nAC:L - The unprotected window spans an entire SPI/I\u00b2C bus transfer of up to 64 bytes, and the attacker can keep one channel transmitting continuously to re-arm the race indefinitely at no cost. The upstream report confirms the corruption occurs spontaneously under normal dual-channel traffic, so no condition beyond the attacker\u0027s control is required.\nPR:L - The attacker needs only open/read/write access to one of the chip\u0027s tty nodes, which on the embedded, industrial and automotive systems using SC16IS75x/76x bridges is granted to ordinary users via the dialout group or service accounts. No CAP_SYS_ADMIN or root is required anywhere on the path.\nUI:N - The race is triggered by the attacker\u0027s own writes racing against ambient traffic on the sibling channel; no victim action is needed. The victim process is affected simply by using its own serial port normally.\nS:U - The vulnerable driver and all impacted resources (the tty ports it manages) are within the same kernel security authority. No VM, IOMMU or sandbox boundary is crossed.\nC:H - The race copies one channel\u0027s data into the other\u0027s stream in both directions \u2014 channel A\u0027s received bytes are emitted on channel B\u0027s physical wire, and channel B\u0027s transmit payload appears in channel A\u0027s tty read buffer where a different, lower-privileged user can read it. Because the attacker can sustain the race by flooding its own channel, a large fraction of the victim channel\u0027s traffic (console output, credentials, modem/AT sequences, metering or control data) can be harvested over time.\nI:H - Attacker-supplied bytes written to one tty are injected into the other channel\u0027s receive stream and are consumed by the victim as legitimate serial input \u2014 including passing through `uart_handle_sysrq_char()` on a console channel \u2014 while the victim\u0027s intended TX payload is silently replaced with foreign data on the wire. This is unauthenticated modification of another security context\u0027s data stream and of the commands actually delivered to attached hardware.\nA:H - Data taken from `xmit_fifo` by `uart_fifo_out()` is destroyed when overwritten, so the victim channel\u0027s traffic is permanently lost, and the attacker can sustain this by keeping its own channel busy. For the RS-485 control buses, modem links and serial consoles these bridge chips serve, continuous corruption renders the link unusable \u2014 a total loss of that communication resource."
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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