CVE-2025-21853
bpf: avoid holding freeze_mutex during mmap operation
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bpf: avoid holding freeze_mutex during mmap operation
In the Linux kernel, the following vulnerability has been resolved: bpf: avoid holding freeze_mutex during mmap operation We use map->freeze_mutex to prevent races between map_freeze() and memory mapping BPF map contents with writable permissions. The way we naively do this means we'll hold freeze_mutex for entire duration of all the mm and VMA manipulations, which is completely unnecessary. This can potentially also lead to deadlocks, as reported by syzbot in [0]. So, instead, hold freeze_mutex only during writeability checks, bump (proactively) "write active" count for the map, unlock the mutex and proceed with mmap logic. And only if something went wrong during mmap logic, then undo that "write active" counter increment. [0] https://lore.kernel.org/bpf/678dcbc9.050a0220.303755.0066.GAE@google.com/
Reserved 2024-12-29 | Published 2025-03-12 | Updated 2025-03-12 | Assigner Linuxgit.kernel.org/...c/29cfda62ab4d92ab94123813db49ab76c1e61b29
git.kernel.org/...c/d95607a5f2f9bb08194c9deaf4a5f3e8ba59a9d4
git.kernel.org/...c/271e49f8a58edba65bc2b1250a0abaa98c4bfdbe
git.kernel.org/...c/bc27c52eea189e8f7492d40739b7746d67b65beb
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