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In the Linux kernel, the following vulnerability has been resolved:
nfsd: decrease sc_count directly if fail to queue dl_recall
A deadlock warning occurred when invoking nfs4_put_stid following a failed
dl_recall queue operation:
T1 T2
nfs4_laundromat
nfs4_get_client_reaplist
nfs4_anylock_blockers
__break_lease
spin_lock // ctx->flc_lock
spin_lock // clp->cl_lock
nfs4_lockowner_has_blockers
locks_owner_has_blockers
spin_lock // flctx->flc_lock
nfsd_break_deleg_cb
nfsd_break_one_deleg
nfs4_put_stid
refcount_dec_and_lock
spin_lock // clp->cl_lock
When a file is opened, an nfs4_delegation is allocated with sc_count
initialized to 1, and the file_lease holds a reference to the delegation.
The file_lease is then associated with the file through kernel_setlease.
The disassociation is performed in nfsd4_delegreturn via the following
call chain:
nfsd4_delegreturn --> destroy_delegation --> destroy_unhashed_deleg -->
nfs4_unlock_deleg_lease --> kernel_setlease --> generic_delete_lease
The corresponding sc_count reference will be released after this
disassociation.
Since nfsd_break_one_deleg executes while holding the flc_lock, the
disassociation process becomes blocked when attempting to acquire flc_lock
in generic_delete_lease. This means:
1) sc_count in nfsd_break_one_deleg will not be decremented to 0;
2) The nfs4_put_stid called by nfsd_break_one_deleg will not attempt to
acquire cl_lock;
3) Consequently, no deadlock condition is created.
Given that sc_count in nfsd_break_one_deleg remains non-zero, we can
safely perform refcount_dec on sc_count directly. This approach
effectively avoids triggering deadlock warnings.
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OR
*cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
Added
CPE Configuration
OR
*cpe:2.3:o:linux:linux_kernel:6.15:rc1:*:*:*:*:*:*
*cpe:2.3:o:linux:linux_kernel:6.15:rc2:*:*:*:*:*:*
*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.12.23 up to (excluding) 6.12.25
*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13.11 up to (excluding) 6.14
*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.14.2 up to (excluding) 6.14.4
*cpe:2.3:o:linux:linux_kernel:5.10.236:*:*:*:*:*:*:*
*cpe:2.3:o:linux:linux_kernel:5.15.180:*:*:*:*:*:*:*
*cpe:2.3:o:linux:linux_kernel:6.1.134:*:*:*:*:*:*:*
*cpe:2.3:o:linux:linux_kernel:6.6.87:*:*:*:*:*:*:*
Added
Reference Type
CVE: https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html Types: Mailing List, Third Party Advisory
Added
Reference Type
CVE: https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html Types: Mailing List, Third Party Advisory
New CVE Received from kernel.org5/09/2025 3:16:08 AM
Action
Type
Old Value
New Value
Added
Description
In the Linux kernel, the following vulnerability has been resolved:
nfsd: decrease sc_count directly if fail to queue dl_recall
A deadlock warning occurred when invoking nfs4_put_stid following a failed
dl_recall queue operation:
T1 T2
nfs4_laundromat
nfs4_get_client_reaplist
nfs4_anylock_blockers
__break_lease
spin_lock // ctx->flc_lock
spin_lock // clp->cl_lock
nfs4_lockowner_has_blockers
locks_owner_has_blockers
spin_lock // flctx->flc_lock
nfsd_break_deleg_cb
nfsd_break_one_deleg
nfs4_put_stid
refcount_dec_and_lock
spin_lock // clp->cl_lock
When a file is opened, an nfs4_delegation is allocated with sc_count
initialized to 1, and the file_lease holds a reference to the delegation.
The file_lease is then associated with the file through kernel_setlease.
The disassociation is performed in nfsd4_delegreturn via the following
call chain:
nfsd4_delegreturn --> destroy_delegation --> destroy_unhashed_deleg -->
nfs4_unlock_deleg_lease --> kernel_setlease --> generic_delete_lease
The corresponding sc_count reference will be released after this
disassociation.
Since nfsd_break_one_deleg executes while holding the flc_lock, the
disassociation process becomes blocked when attempting to acquire flc_lock
in generic_delete_lease. This means:
1) sc_count in nfsd_break_one_deleg will not be decremented to 0;
2) The nfs4_put_stid called by nfsd_break_one_deleg will not attempt to
acquire cl_lock;
3) Consequently, no deadlock condition is created.
Given that sc_count in nfsd_break_one_deleg remains non-zero, we can
safely perform refcount_dec on sc_count directly. This approach
effectively avoids triggering deadlock warnings.