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NFSD: fix use-after-free in __nfs42_ssc_open()

Benjamin Coddington requested to merge bcodding/centos-stream-9:bz2152816_CVE-2022-4379 into main

NFSD: fix use-after-free in __nfs42_ssc_open()

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2152816
CVE: CVE-2022-4379
Conflicts: Slight context diff from upstream patch, as we've not yet taken
upstream commit 754035ff7. This resulting fix is unchanged.

commit 75333d48f92256a0dec91dbf07835e804fc411c0
Author: Dai Ngo dai.ngo@oracle.com
Date: Mon Dec 12 14:50:11 2022 -0800

NFSD: fix use-after-free in __nfs42_ssc_open()

Problem caused by source's vfsmount being unmounted but remains
on the delayed unmount list. This happens when nfs42_ssc_open()
return errors.

Fixed by removing nfsd4_interssc_connect(), leave the vfsmount
for the laundromat to unmount when idle time expires.

We don't need to call nfs_do_sb_deactive when nfs42_ssc_open
return errors since the file was not opened so nfs_server->active
was not incremented. Same as in nfsd4_copy, if we fail to
launch nfsd4_do_async_copy thread then there's no need to
call nfs_do_sb_deactive

Reported-by: Xingyuan Mo <hdthky0@gmail.com>
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Tested-by: Xingyuan Mo <hdthky0@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Signed-off-by: Benjamin Coddington bcodding@redhat.com

Edited by Benjamin Coddington

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