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nfsd: fix leaked file lock with nfs exported overlayfs

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nfsd and lockd call vfs_lock_file() to lock/unlock the inode
returned by locks_inode(file).

Many places in nfsd/lockd code use the inode returned by
file_inode(file) for lock manipulation. With Overlayfs, file_inode()
(the underlying inode) is not the same object as locks_inode() (the
overlay inode). This can result in "Leaked POSIX lock" messages
and eventually to a kernel crash as reported by Eddie Horng:
https://marc.info/?l=linux-unionfs&m=153086643202072&w=2

Fix all the call sites in nfsd/lockd that should use locks_inode().
This is a correctness bug that manifested when overlayfs gained
NFS export support in v4.16.

Reported-by: Eddie Horng <eddiehorng.tw@gmail.com>
Tested-by: Eddie Horng <eddiehorng.tw@gmail.com>
Cc: Jeff Layton <jlayton@kernel.org>
Fixes: 8383f17488 ("ovl: wire up NFS export operations")
Cc: stable@vger.kernel.org
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Amir Goldstein
2018-07-13 17:22:24 +03:00
committed by J. Bruce Fields
parent 8163496e78
commit 64bed6cbe3
6 changed files with 15 additions and 15 deletions
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4
include/linux/lockd/lockd.h
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@@ -299,7 +299,7 @@ int nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr);
static inline struct inode *nlmsvc_file_inode(struct nlm_file *file)
{
return file_inode(file->f_file);
return locks_inode(file->f_file);
}
static inline int __nlm_privileged_request4(const struct sockaddr *sap)
@@ -359,7 +359,7 @@ static inline int nlm_privileged_requester(const struct svc_rqst *rqstp)
static inline int nlm_compare_locks(const struct file_lock *fl1,
const struct file_lock *fl2)
{
return file_inode(fl1->fl_file) == file_inode(fl2->fl_file)
return locks_inode(fl1->fl_file) == locks_inode(fl2->fl_file)
&& fl1->fl_pid == fl2->fl_pid
&& fl1->fl_owner == fl2->fl_owner
&& fl1->fl_start == fl2->fl_start