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CVE-2026-46325
RDMA/rxe: Fix iova-to-va conversion for MR page sizes != PAGE_SIZE
Published 2026-06-09 (4 months ago) by the Linux kernel CNA. Subsystem drivers/infiniband. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-46325 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 6.18.14-1 | Update the kernel and reboot. Fixed in 6.18.14-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.18.14-1 | Update the kernel and reboot. Fixed in 6.18.14-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The current implementation incorrectly handles memory regions (MRs) with page sizes different from the system PAGE_SIZE. The core issue is that rxe_set_page() is called with mr->page_size step increments, but the page_list stores individual struct page pointers, each representing PAGE_SIZE of memory. ib_sg_to_page() has ensured that when i>=1 either a) SG[i-1].dma_end and SG[i].dma_addr are contiguous or b) SG[i-1].dma_end and SG[i].dma_addr are mr->page_size aligned. This leads to incorrect iova-to-va conversion in scenarios: 1) page_size < PAGE_SIZE (e.g., MR: 4K, system: 64K): ibmr->iova = 0x181800 sg[0]: dma_addr=0x181800, len=0x800 sg[1]: dma_addr=0x173000, len=0x1000 Access iova = 0x181800 + 0x810 = 0x182010 Expected VA: 0x173010 (second SG, offset 0x10) Before fix: - index = (0x182010 >> 12) - (0x181800 >> 12) = 1 - page_offset = 0x182010 & 0xFFF = 0x10 - xarray[1] stores system page base 0x170000 - Resulting VA: 0x170000 + 0x10 = 0x170010 (wrong) 2) page_size > PAGE_SIZE (e.g., MR: 64K, system: 4K): ibmr->iova = 0x18f800 sg[0]: dma_addr=0x18f800, len=0x800 sg[1]: dma_addr=0x170000, len=0x1000 Access iova = 0x18f800 + 0x810 = 0x190010 Expected VA: 0x170010 (second SG, offset 0x10) Before fix: - index = (0x190010 >> 16) - (0x18f800 >> 16) = 1 - page_offset = 0x190010 & 0xFFFF = 0x10 - xarray[1] stores system page for dma_addr 0x170000 - Resulting VA: system page of 0x170000 + 0x10 = 0x170010 (wrong) Yi Zhang reported a kernel panic[1] years ago related to this defect. Solution: 1. Replace xarray with pre-allocated rxe_mr_page array for sequential indexing (all MR page indices are contiguous) 2. Each rxe_mr_page stores both struct page* and offset within the system page 3. Handle MR page_size != PAGE_SIZE relationships: - page_size > PAGE_SIZE: Split MR pages into multiple system pages - page_size <= PAGE_SIZE: Store offset within system page 4. Add boundary checks and compatibility validation This ensures correct iova-to-va conversion regardless of MR page size and system PAGE_SIZE relationship, while improving performance through array-based sequential access. Tests on 4K and 64K PAGE_SIZE hosts: - rdma-core/pytests $ ./build/bin/run_tests.py --dev eth0_rxe - blktest: $ TIMEOUT=30 QUICK_RUN=1 USE_RXE=1 NVMET_TRTYPES=rdma ./check nvme srp rnbd [1] https://lore.kernel.org/all/CAHj4cs9XRqE25jyVw9rj9YugffLn5+f=1znaBEnu1usLOciD+g@mail.gmail.com/T/
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/infiniband/sw/rxe/rxe_mr.c
drivers/infiniband/sw/rxe/rxe_verbs.h
- What this is
- SOFT-ROCE DRIVER (rxe)MAINTAINERS section matched on drivers/infiniband/sw/rxe/ · linux-rdma@vger.kernel.org · Supported
- Kernel module
- rdma_rxe
Check it on the machine
grep -wE 'CONFIG_INFINIBAND|CONFIG_RDMA_RXE' /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 rdma_rxePrints 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.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae
- trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp
- forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_INFINIBAND, CONFIG_RDMA_RXE
- 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
- 2026-06-09 (4 months 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
- 0.35%, higher than 26.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/infiniband
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.3 | 6.18.14 | 409c2c5508f3 |
| 6.3 | 6.19.4 | 836f6c13c967 |
| 6.3 | 7.0 | 12985e5915a0 |
| 6.2.3 | 0 | 0 |
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 bug is reached when rxe processes incoming RoCE packets over UDP (port 4791) on the responder path for RDMA Read, Write, and Atomic operations, which is the standard network-facing deployment for software RoCE storage targets and RDMA services.
- AC:LAttack complexity, low
- Once a victim host runs rxe with an FMR whose page_size differs from PAGE_SIZE, a remote peer can reliably trigger the defective iova-to-VA conversion by sending RDMA operations with IOVAs that cross MR page boundaries, as demonstrated in the fix commit's worked examples.
- PR:NPrivileges required, none
- Exploitation requires no OS privileges on the victim host; a remote attacker only needs network reachability to an established RDMA session (e.g., NVMe-oF or rtrs client) and a valid rkey from that connection, not local root or CAP_NET_ADMIN on the target system.
- UI:NUser interaction, none
- No victim user action is required beyond normal operation of an RDMA-connected service; the attacker triggers the flaw by sending crafted RDMA packets over an existing queue pair.
- S:UScope, unchanged
- Impact is confined to kernel memory corruption and crashes within the same kernel security boundary; this is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.
- C:HConfidentiality impact, high
- Incorrect iova-to-VA mapping causes memcpy and atomic handlers to read from the wrong struct page, enabling disclosure of data from unintended pages within the MR mapping and constituting out-of-bounds kernel memory read.
- I:HIntegrity impact, high
- RDMA Write and Atomic Write operations using the buggy conversion write to incorrectly resolved virtual addresses, corrupting kernel memory outside the intended MR buffer and providing a memory-corruption primitive exploitable for further compromise.
- A:HAvailability impact, high
- The fix commit cites a confirmed kernel panic from this defect, and misresolved page mappings in rxe_mr_copy() can cause oopses or crashes when accessing invalid or misaligned memory.