filelock: prevent FL_LEASE and FL_DELEG flavor confusion in generic_add_lease() - #2616
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…dd_lease() generic_add_lease() searches ctx->flc_lease for an existing entry matching (flc_file == filp && flc_owner == lease->c.flc_owner) in order to modify an existing lease in place via lease_modify(). However, it does not verify that the existing entry's flavor (FL_LEASE vs FL_DELEG) matches the newly requested lease's flavor in flc_flags. Since both F_SETLEASE and F_SETDELEG pass filp as flc_owner from userland (fcntl_setlease() and fcntl_setdeleg()), calling F_SETDELEG on a file descriptor that already holds an FL_LEASE modifies flc_type in place and returns 0 without setting FL_DELEG in flc_flags. Conversely, calling F_SETLEASE on a file descriptor that holds an active FL_DELEG modifies the delegation in place without holding inode_lock() (which vfs_setlease() only acquires when is_deleg is true). Reject cross-flavor modifications in generic_add_lease() when the existing entry on ctx->flc_lease has a different (FL_LEASE | FL_DELEG) flag mask from the requested lease. Fixes: 1602bad ("vfs: expose delegation support to userland") Assisted-by: LLM Signed-off-by: Hui Peng <benquike@gmail.com>
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Series: https://patchwork.kernel.org/project/linux-fsdevel/list/?series=1169405
Submitter: Hui Peng
Version: 1
Patches: 1/1
Message-ID:
<20260919210617.3028917-1-benquike@gmail.com>Base: vfs.base.ci
Lore: https://lore.kernel.org/linux-fsdevel/20260919210617.3028917-1-benquike@gmail.com
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