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After the vnode unlock, mount point might be destroyed immediately,

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dropping the reference on mnt_cred. Prevent this by referencing the
temporal credentials before unlock.

Tested by:	pho
Reviewed by:	dfr
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Approved by:	re (gjb)
This commit is contained in:
Konstantin Belousov 2016-06-18 20:22:53 +00:00
parent cacbedfc46
commit c7239ca41a
1 changed files with 9 additions and 5 deletions
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14
sys/nlm/nlm_advlock.c
View File

@ -210,7 +210,7 @@ nlm_advlock_internal(struct vnode *vp, void *id, int op, struct flock *fl,
struct rpc_callextra ext;
struct nlm_feedback_arg nf;
AUTH *auth;
struct ucred *cred;
struct ucred *cred, *cred1;
struct nlm_file_svid *ns;
int svid;
int error;
@ -240,15 +240,17 @@ nlm_advlock_internal(struct vnode *vp, void *id, int op, struct flock *fl,
else
retries = INT_MAX;
if (unlock_vp)
VOP_UNLOCK(vp, 0);
/*
* We need to switch to mount-point creds so that we can send
* packets from a privileged port.
* packets from a privileged port. Reference mnt_cred and
* switch to them before unlocking the vnode, since mount
* point could be unmounted right after unlock.
*/
cred = td->td_ucred;
td->td_ucred = vp->v_mount->mnt_cred;
crhold(td->td_ucred);
if (unlock_vp)
VOP_UNLOCK(vp, 0);
host = nlm_find_host_by_name(servername, sa, vers);
auth = authunix_create(cred);
@ -373,7 +375,9 @@ nlm_advlock_internal(struct vnode *vp, void *id, int op, struct flock *fl,
if (ns)
nlm_free_svid(ns);
cred1 = td->td_ucred;
td->td_ucred = cred;
crfree(cred1);
AUTH_DESTROY(auth);
nlm_host_release(host);