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CVE Record

CVE-2023-53742: kcsan: Avoid READ_ONCE() in read_instrumented_memory()

In the Linux kernel, the following vulnerability has been resolved: kcsan: Avoid READ_ONCE() in read_instrumented_memory() Haibo Li reported: | Unable to handle kernel paging request at virtual address | ffffff802a0d8d7171 | Mem abort info:o: | ESR = 0x9600002121 | EC = 0x25: DABT (current EL), IL = 32 bitsts | SET = 0, FnV = 0 0 | EA = 0, S1PTW = 0 0 | FSC = 0x21: alignment fault | Data abort info:o: | ISV = 0, ISS = 0x0000002121 | CM = 0, WnR = 0 0 | swapper pgtable: 4k pages, 39-bit VAs, pgdp=000000002835200000 | [ffffff802a0d8d71] pgd=180000005fbf9003, p4d=180000005fbf9003, | pud=180000005fbf9003, pmd=180000005fbe8003, pte=006800002a0d8707 | Internal error: Oops: 96000021 [#1] PREEMPT SMP | Modules linked in: | CPU: 2 PID: 45 Comm: kworker/u8:2 Not tainted | 5.15.78-android13-8-g63561175bbda-dirty #1 | ... | pc : kcsan_setup_watchpoint+0x26c/0x6bc | lr : kcsan_setup_watchpoint+0x88/0x6bc | sp : ffffffc00ab4b7f0 | x29: ffffffc00ab4b800 x28: ffffff80294fe588 x27: 0000000000000001 | x26: 0000000000000019 x25: 0000000000000001 x24: ffffff80294fdb80 | x23: 0000000000000000 x22: ffffffc00a70fb68 x21: ffffff802a0d8d71 | x20: 0000000000000002 x19: 0000000000000000 x18: ffffffc00a9bd060 | x17: 0000000000000001 x16: 0000000000000000 x15: ffffffc00a59f000 | x14: 0000000000000001 x13: 0000000000000000 x12: ffffffc00a70faa0 | x11: 00000000aaaaaaab x10: 0000000000000054 x9 : ffffffc00839adf8 | x8 : ffffffc009b4cf00 x7 : 0000000000000000 x6 : 0000000000000007 | x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffffffc00a70fb70 | x2 : 0005ff802a0d8d71 x1 : 0000000000000000 x0 : 0000000000000000 | Call trace: | kcsan_setup_watchpoint+0x26c/0x6bc | __tsan_read2+0x1f0/0x234 | inflate_fast+0x498/0x750 | zlib_inflate+0x1304/0x2384 | __gunzip+0x3a0/0x45c | gunzip+0x20/0x30 | unpack_to_rootfs+0x2a8/0x3fc | do_populate_rootfs+0xe8/0x11c | async_run_entry_fn+0x58/0x1bc | process_one_work+0x3ec/0x738 | worker_thread+0x4c4/0x838 | kthread+0x20c/0x258 | ret_from_fork+0x10/0x20 | Code: b8bfc2a8 2a0803f7 14000007 d503249f (78bfc2a8) ) | ---[ end trace 613a943cb0a572b6 ]----- The reason for this is that on certain arm64 configuration since e35123d83ee3 ("arm64: lto: Strengthen READ_ONCE() to acquire when CONFIG_LTO=y"), READ_ONCE() may be promoted to a full atomic acquire instruction which cannot be used on unaligned addresses. Fix it by avoiding READ_ONCE() in read_instrumented_memory(), and simply forcing the compiler to do the required access by casting to the appropriate volatile type. In terms of generated code this currently only affects architectures that do not use the default READ_ONCE() implementation. The only downside is that we are not guaranteed atomicity of the access itself, although on most architectures a plain load up to machine word size should still be atomic (a fact the default READ_ONCE() still relies on itself).

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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can crash affected systems when KCSAN reads instrumented memory on certain arm64 LTO configurations. The source describes a kernel paging request and alignment fault, not data theft or privilege escalation. Public severity and CVSS are not provided in the bundle.

Executive priority

Treat this as a targeted kernel stability issue until vendor severity is available. It merits attention for custom Android, embedded, test, or specialized Linux builds, but the source bundle does not support emergency exploitation claims.

Technical view

READ_ONCE() in kcsan read_instrumented_memory() could become a full atomic acquire load on some arm64 CONFIG_LTO builds. Atomic acquire loads cannot safely handle unaligned addresses, causing an alignment fault and kernel Oops. The fix avoids READ_ONCE() and uses a volatile typed access.

Likely exposure

Exposure appears limited to Linux kernels using the affected KCSAN path on architectures/configurations where READ_ONCE() is strengthened, specifically noted for arm64 with CONFIG_LTO. The affected version data in the bundle is incomplete or ambiguous, so teams should verify exact kernel branches against vendor advisories.

Exploitation context

The bundle provides no evidence of active exploitation, no KEV listing, and no public exploit status. The described impact is a kernel crash during instrumented memory reads, with the example occurring during boot-time rootfs population.

Researcher notes

Key uncertainty is exposure scope. The source names the failing mechanism and fix but provides no CVSS, CWE, exploitability assessment, or clear version range semantics. Validate branch-specific backports before declaring systems unaffected.

Mitigation direction

  • Check your Linux vendor advisory for the fixed kernel package or backport.
  • Prioritize kernels built for arm64 with CONFIG_LTO and KCSAN enabled.
  • Apply kernel updates containing the referenced stable commits when available.
  • If no vendor fix exists, track upstream stable branches for backports.

Validation and detection

  • Inventory Linux kernel versions and build configurations across affected fleets.
  • Confirm whether KCSAN and arm64 LTO are enabled in relevant builds.
  • Compare running kernels with the referenced stable commit fixes.
  • Review crash logs for alignment faults in kcsan_setup_watchpoint.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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0CVSS vectors
3Timeline events
0ADP providers
5Source links

Vulnerability timeline

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  2. CVE publishedCVE Program

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxdfd402a4c4baae42398ce9180ff424d589b8bffc, dfd402a4c4baae42398ce9180ff424d589b8bffc, dfd402a4c4baae42398ce9180ff424d589b8bffc, dfd402a4c4baae42398ce9180ff424d589b8bffcunaffected
LinuxLinux5.8, 0, 6.1.28, 6.2.15, 6.3.2, 6.4affected
Weakness

CWE details

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