Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: memcg: use round-robin victim selection in refill_stock Harry Yoo reported that get_random_u32_below() is not safe to call in the nmi context and memcg charge draining can happen in nmi context. More specifically get_random_u32_below() is neither reentrant- nor NMI-safe: it acquires a per-cpu local_lock via local_lock_irqsave() on the batched_entropy_u32 state. An NMI that lands on a CPU mid-update of the ChaCha batch state and recurses into the random subsystem would corrupt that state. The memcg_stock local_trylock prevents re-entry on the percpu stock itself, but cannot protect an unrelated subsystem's per-cpu lock. Replace the random pick with a per-cpu round-robin counter stored in memcg_stock_pcp and serialized by the same local_trylock that already guards cached[] and nr_pages[]. No atomics, no random calls, no extra locks needed.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected f735eebe55f8f61758fe014bd0b02ab50b059e4d before 89bd8215e25aa6999cc51696da418e0d422bc5e0; affected f735eebe55f8f61758fe014bd0b02ab50b059e4d before 00731bd7e18f182a32ca54d6b176eaa470b51ed7; affected f735eebe55f8f61758fe014bd0b02ab50b059e4d before c0cafe24d3f6534294c4b2bc2d47734ff7cbd313 |
| Linux / Linux | affected 6.16; unaffected 0 before 6.16; unaffected 6.18.36 through 6.18.*; unaffected 7.0.13 through 7.0.*; unaffected 7.1 through * |
CWE
No CWE identifiers supplied.