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CVE-2026-80748
mmc: loongson2: Fix sg iteration in data reorder functions
Published 2026-09-03 (2 months ago) by the Linux kernel CNA. Subsystem drivers/mmc. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-80748 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 | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
In ls2k0500_mmc_reorder_cmd_data() and ls2k2000_mmc_reorder_cmd_data(), the for_each_sg() macro already iterates over the scatterlist entries, with 'sg' pointing to the current entry. However, the code incorrectly uses '&sg[i]' and 'sg_dma_len(&sg[i])' inside the loop, which treats 'sg' as an array base and indexes it again, leading to access of wrong sg entries (or out-of-bounds if the list is not an array).
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/mmc/host/loongson2-mmc.c
- What this is
- LOONGSON-2 SOC SERIES MMC/SD/SDIO CONTROLLER DRIVERMAINTAINERS section matched on drivers/mmc/host/loongson2-mmc.c · linux-mmc@vger.kernel.org · Maintained
Check it on the machine
grep -w CONFIG_MMC_LOONGSON2 /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.
Show whether Debian builds this, per release
Debian does not build this code in 2 releases. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidn
- ?
- not established - no Makefile entry for the affected file
- n
- not enabled on any flavour - this release does not build the code
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switch
- CONFIG_MMC_LOONGSON2
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
- 2026-09-03 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 6.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/mmc
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.17 | 6.18.46 | 8f7f7a6d5aed |
| 6.17 | 7.1.10 | db368164383c |
| 6.17 | 7.2 | 00179ed9fbe0 |
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:LAttack vector, local
- The flaw is in the Loongson-2K MMC host driver reached via local block I/O and MMC ioctls (SD writes trigger SD_APP_SEND_NUM_WR_BLKS; card init issues SD_SWITCH/SCR), not via any network protocol; it affects LoongArch desktops, kiosks, and embedded systems with SD/eMMC slots.
- AC:LAttack complexity, low
- An attacker with SD-backed storage access can reliably drive the post-DMA reorder path on every qualifying transfer; the double-indexed for_each_sg bug deterministically accesses wrong scatterlist entries whenever sg_len exceeds one, without races or uncontrollable memory layout.
- PR:LPrivileges required, low
- Any unprivileged local user writing to an SD-backed filesystem or opening the mmc block device can trigger the vulnerable reorder functions; no CAP_SYS_ADMIN, init-namespace root, or user-namespace capability is required.
- UI:NUser interaction, none
- Exploitation requires only the attacker's own writes, MMC_IOC_CMD ioctl sequences, or kernel auto-enumeration after SD insertion; no separate victim mount, login, or cooperative action is needed.
- S:UScope, unchanged
- Scatterlist mis-indexing corrupts kernel heap memory within the host kernel security boundary; this is standard local privilege-escalation impact, not VM escape, IOMMU bypass, or cross-container authority change.
- C:HConfidentiality impact, high
- sg_virt(&sg[i]) on a mis-advanced pointer reads from wrong or out-of-bounds scatterlist entries, exposing adjacent kernel memory; out-of-bounds reads are rated High and can leak pointers usable for further exploitation.
- I:HIntegrity impact, high
- The reorder loop writes bitrev8x4/cpu_to_be32-transformed values through the mis-indexed scatterlist pointer, performing out-of-bounds kernel memory writes that can corrupt adjacent objects and enable arbitrary code execution.
- A:HAvailability impact, high
- Corrupting adjacent kernel structures via the out-of-bounds scatterlist write can cause immediate kernel oops or panic; memory corruption bugs in interrupt context are rated High availability impact even when not fully weaponized.