EUVD-2026-15372
GHSA-q6xr-q445-2xxh
Lifecycle Timeline
4Description
In the Linux kernel, the following vulnerability has been resolved: tracing: Fix WARN_ON in tracing_buffers_mmap_close When a process forks, the child process copies the parent's VMAs but the user_mapped reference count is not incremented. As a result, when both the parent and child processes exit, tracing_buffers_mmap_close() is called twice. On the second call, user_mapped is already 0, causing the function to return -ENODEV and triggering a WARN_ON. Normally, this isn't an issue as the memory is mapped with VM_DONTCOPY set. But this is only a hint, and the application can call madvise(MADVISE_DOFORK) which resets the VM_DONTCOPY flag. When the application does that, it can trigger this issue on fork. Fix it by incrementing the user_mapped reference count without re-mapping the pages in the VMA's open callback.
Analysis
A reference counting vulnerability in the Linux kernel's tracing subsystem causes a WARN_ON to trigger when a process forks and both parent and child processes exit, particularly when the application calls madvise(MADV_DOFORK) to enable VMA copy-on-fork behavior. The vulnerability affects all Linux kernel versions with the vulnerable tracing_buffers_mmap code and allows local attackers to cause a kernel warning that may lead to denial of service or information disclosure through the kernel warning itself. …
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Priority Score
Vendor Status
Debian
| Release | Status | Fixed Version | Urgency |
|---|---|---|---|
| bullseye | not-affected | - | - |
| bullseye (security) | fixed | 5.10.251-1 | - |
| bookworm | not-affected | - | - |
| bookworm (security) | fixed | 6.1.164-1 | - |
| trixie | vulnerable | 6.12.73-1 | - |
| trixie (security) | vulnerable | 6.12.74-2 | - |
| forky, sid | fixed | 6.19.8-1 | - |
| (unstable) | fixed | 6.19.8-1 | - |
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External POC / Exploit Code
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