fuse: alloc pqueue before installing fch in fuse_dev

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Prior to this patchset, fuse_dev (containing fuse_pqueue) was allocated on
mount.  But now fuse_dev is allocated when opening /dev/fuse, even though
the queues are not needed at that time.

Delay allocation of the pqueue (4k worth of list_head) just before mounting
or cloning a device.

Various distributions (e.g. Debian/Fedora) configure /dev/fuse as world
writable, so the pqueue allocation should be deferred to a privileged
operation (mount) to prevent unprivileged userspace from consuming pinned
kernel memory.

[Li Wang: fix kernel NULL pointer dereference in fuse_uring_add_to_pq()]
[Fix race in fuse_dev_release()]

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

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This commit is contained in:

Miklos Szeredi 2026-04-02 14:49:09 +02:00

parent c0f817320d

commit 48649c0603

3 changed files with 67 additions and 24 deletions

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82

fs/fuse/dev.c

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4

fs/fuse/dev_uring.c

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5

fs/fuse/fuse_dev_i.h

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