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CVE-2024-40999
net: ena: Add validation for completion descriptors consistency
Published 2024-07-12 (2 years ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2024-40999 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.9.7-1 | Update the kernel and reboot. Fixed in 6.9.7-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 6.9.7-1 | Update the kernel and reboot. Fixed in 6.9.7-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.9.7-1 | Update the kernel and reboot. Fixed in 6.9.7-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Validate that `first` flag is set only for the first descriptor in multi-buffer packets. In case of an invalid descriptor, a reset will occur. A new reset reason for RX data corruption has been added.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/net/ethernet/amazon/ena/ena_eth_com.c
drivers/net/ethernet/amazon/ena/ena_netdev.c
drivers/net/ethernet/amazon/ena/ena_regs_defs.h
- What this is
- AMAZON ETHERNET DRIVERSMAINTAINERS section matched on drivers/net/ethernet/amazon/ · netdev@vger.kernel.org · Maintained
- Kernel module
- ena
Check it on the machine
grep -wE 'CONFIG_ENA_ETHERNET|CONFIG_ETHERNET|CONFIG_NET_VENDOR_AMAZON' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w enaPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormm
- trixieMnot built on armel/rpi, s390x/s390x
- forky, sidMnot built on s390x/s390x
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_ENA_ETHERNET, CONFIG_ETHERNET, CONFIG_NET_VENDOR_AMAZON
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2024-07-12 (2 years ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.53%, higher than 43.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.9 | 6.9.7 | 42146ee5286f |
| 4.9 | 6.10 | b37b98a3a0c1 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- The vulnerable code is the NIC receive completion path (`ena_clean_rx_irq`/`ena_com_rx_pkt`), entered solely as a result of frames arriving from the network, and the multi-descriptor framing logic at fault is only exercised by large/scattered packets a remote peer generates at will. ENA is the standard NIC on internet-facing AWS EC2 instances, so the path is driven by remote, unauthenticated traffic.
- AC:LAttack complexity, low
- No specific memory layout, victim state, or non-default configuration is required; the descriptor-framing path is exercised by ordinary multi-buffer RX traffic and the driver's cross-poll partial-packet state can be driven by sustained large-packet load. Per the rule to choose the higher severity when uncertain, the influenceable device-side framing condition is scored as Low rather than High.
- PR:NPrivileges required, none
- Processing happens in NAPI/softirq context before any socket, filesystem, or authentication layer is reached, so no account or capability on the target is needed. A remote peer simply sends packets to the interface.
- UI:NUser interaction, none
- The RX completion path runs automatically whenever the interface is up and receiving traffic. No victim action of any kind is required.
- S:UScope, unchanged
- The mis-framed descriptors corrupt driver state and skb contents within the same kernel/host security authority. No VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- Merged descriptor chains splice RX buffers belonging to unrelated packets into a single skb delivered to the network stack, and the accumulated `buf_offset`/`buf_len` can describe fragments extending past the real allocation, giving out-of-bounds reads. Stale page pointers reaching `skb_add_rx_frag()` constitute a use-after-free, which is scored High for confidentiality.
- I:HIntegrity impact, high
- The unguarded fragment loop can `page_ref_inc()` and `skb_add_rx_frag()` a stale or already-released page and DMA-unmap an already-unmapped buffer, producing double-free/UAF heap-corruption primitives; corrupted packet data is also injected into the stack. Memory corruption of this kind is exploitable for control-flow hijack and is scored High.
- A:HAvailability impact, high
- A NULL `rx_info->page` reaching `page_ref_inc()`/`skb_add_rx_frag()` is an immediate kernel oops, and even the benign outcome is RX ring desync that stalls buffer replenishment and forces a full device reset, dropping network connectivity. Any kernel crash or hang is scored High.