CVE-2024-35804
KVM: x86: Mark target gfn of emulated atomic instruction as dirty
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: Mark target gfn of emulated atomic instruction as dirty
When emulating an atomic access on behalf of the guest, mark the target
gfn dirty if the CMPXCHG by KVM is attempted and doesn't fault. This
fixes a bug where KVM effectively corrupts guest memory during live
migration by writing to guest memory without informing userspace that the
page is dirty.
Marking the page dirty got unintentionally dropped when KVM's emulated
CMPXCHG was converted to do a user access. Before that, KVM explicitly
mapped the guest page into kernel memory, and marked the page dirty during
the unmap phase.
Mark the page dirty even if the CMPXCHG fails, as the old data is written
back on failure, i.e. the page is still written. The value written is
guaranteed to be the same because the operation is atomic, but KVM's ABI
is that all writes are dirty logged regardless of the value written. And
more importantly, that's what KVM did before the buggy commit.
Huge kudos to the folks on the Cc list (and many others), who did all the
actual work of triaging and debugging.
base-commit: 6769ea8da8a93ed4630f1ce64df6aafcaabfce64
En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: KVM: x86: marcar el gfn de destino de la instrucción atómica emulada como sucia Al emular un acceso atómico en nombre del invitado, marque el gfn de destino como sucio si se intenta realizar el CMPXCHG por KVM y no falla. Esto corrige un error por el cual KVM corrompe efectivamente la memoria del invitado durante la migración en vivo al escribir en la memoria del invitado sin informar al espacio de usuario que la página está sucia. Marcar la página como sucia se eliminó involuntariamente cuando el CMPXCHG emulado de KVM se convirtió para realizar un acceso de usuario. Antes de eso, KVM asignaba explícitamente la página invitada a la memoria del kernel y marcaba la página como sucia durante la fase de desasignación. Marque la página como sucia incluso si CMPXCHG falla, ya que los datos antiguos se vuelven a escribir en caso de fallo, es decir, la página aún está escrita. Se garantiza que el valor escrito será el mismo porque la operación es atómica, pero la ABI de KVM es que todas las escrituras se registran de forma sucia independientemente del valor escrito. Y lo que es más importante, eso es lo que hizo KVM antes de la confirmación del error. Felicitaciones enormes a las personas en la lista Cc (y a muchos otros), que hicieron todo el trabajo de clasificación y depuración. confirmación base: 6769ea8da8a93ed4630f1ce64df6aafcaabfce64
CVSS Scores
SSVC
- Decision:Track
Timeline
- 2024-05-17 CVE Reserved
- 2024-05-17 CVE Published
- 2024-05-18 EPSS Updated
- 2024-08-02 CVE Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
CAPEC
References (9)
| URL | Tag | Source |
|---|---|---|
| https://git.kernel.org/stable/c/d97c0667c1e61ded6639117b4b9584a9c12b7e66 | Vuln. Introduced | |
| https://git.kernel.org/stable/c/1c2361f667f3648855ceae25f1332c18413fdb9f | Vuln. Introduced | |
| https://git.kernel.org/stable/c/b0f294103f4cf733e23d3f0c4e5fd58e42998921 | Vuln. Introduced | |
| https://git.kernel.org/stable/c/e964665cc7ca13a16992b205fce63554b9efc78b | Vuln. Introduced |
| URL | Date | SRC |
|---|
| URL | Date | SRC |
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Affected Vendors, Products, and Versions
| Vendor | Product | Version | Other | Status | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.15.58 < 5.15.154 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.15.58 < 5.15.154" | en |
Affected
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| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.19 < 6.1.84 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.19 < 6.1.84" | en |
Affected
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| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.19 < 6.6.24 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.19 < 6.6.24" | en |
Affected
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| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.19 < 6.7.12 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.19 < 6.7.12" | en |
Affected
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| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.19 < 6.8 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.19 < 6.8" | en |
Affected
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| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | 5.17.13 Search vendor "Linux" for product "Linux Kernel" and version "5.17.13" | en |
Affected
| ||||||
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | 5.18.2 Search vendor "Linux" for product "Linux Kernel" and version "5.18.2" | en |
Affected
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