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CVE-2026-74483: Linux

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CVSS

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Вероятност да бъде експлоатирана в следващите 30 дни (EPSS)

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    Описание

    Оригинално описание

    In the Linux kernel, the following vulnerability has been resolved: binfmt_misc: don't leak the user namespace when the mount fails bm_get_tree() takes a reference to the user namespace and hands it to get_tree_keyed() as the sget key. sget_fc() moves that reference into sb->s_fs_info and clears fc->s_fs_info, so from that point on the superblock owns it and bm_free() doesn't see it anymore. The superblock drops it in ->put_super(). But generic_shutdown_super() only calls ->put_super() from inside the if (sb->s_root) branch, so nothing releases it when bm_fill_super() fails: - The kzalloc_obj() failure leaves s_root NULL and the whole branch is skipped. - A simple_fill_super() failure in the file loop leaves s_root set, but s_op still points at simple_super_operations, which has no ->put_super(). bm_fill_super() installs s_ops only once simple_fill_super() returned success, and installing it earlier wouldn't help either because simple_fill_super() overwrites s_op. Either way vfs_get_super() calls deactivate_locked_super() and the reference is gone for good. binfmt_misc mounts are available in a user namespace and both the inode and the dentry cache are SLAB_ACCOUNT, so an unprivileged caller under a tight memory cgroup can fail simple_fill_super() on demand and leak one user namespace per attempt. Drop the reference in ->kill_sb() instead, which runs unconditionally, the same way nfsd and rpc_pipefs release their keyed s_fs_info. That also stops ->put_super() from clearing s_fs_info while the superblock is still on @fs_supers. generic_shutdown_super() leaves it there on purpose so that sget_fc() keeps finding it until kill_sb() has run, but a NULL s_fs_info makes test_keyed_super() miss it, so a concurrent mount for the same user namespace skips the grab_super() wait and creates a second superblock for a namespace that is still being torn down.

    Засегнати продукти

    • Linux Linux: 21ca59b365c091d583f36ac753eaa8baf947be6f преди ffec017158d3aad8a6ffca1dfad63d63bde9caad; 21ca59b365c091d583f36ac753eaa8baf947be6f преди 867aed6a4848761190d5ebdedf9642648f97bceb; 21ca59b365c091d583f36ac753eaa8baf947be6f преди 87a4eb9bbb3497f749bbac612af22ddaa62d7b0d; 21ca59b365c091d583f36ac753eaa8baf947be6f преди b8206f516fe7cbe785cf44bf09c17c438d7c3cad
    • Linux Linux: 6.7; преди 6.7; 6.12.105 до 6.12.*; 6.18.46 до 6.18.*; 7.1.8 до 7.1.*; 7.2 до *

    История

    • 15 август 2026 Публикувано

    Други уязвимости в Linux Linux

    Първоизточници

    CVE-2026-74483: Linux | freedomonline.bg