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nfsd: remove unsafe BUG_ON from set_change_info

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At one time, nfsd would scrape inode information directly out of struct
inode in order to populate the change_info4. At that time, the BUG_ON in
set_change_info made some sense, since having it unset meant a coding
error.

More recently, it calls vfs_getattr to get this information, which can
fail. If that fails, fh_pre_saved can end up not being set. While this
situation is unfortunate, we don't need to crash the box.

Move set_change_info to nfs4proc.c since all of the callers are there.
Revise the condition for setting "atomic" to also check for
fh_pre_saved. Drop the BUG_ON and just have it zero out both
change_attr4s when this occurs.

Reported-by: Boyang Xue <bxue@redhat.com>
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2223560
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Jeff Layton 2023-07-21 10:29:11 -04:00 committed by Chuck Lever
parent a332018a91
commit 976626073a
2 changed files with 32 additions and 11 deletions
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32
fs/nfsd/nfs4proc.c
View File

@ -382,6 +382,38 @@ out:
return status;
}
/**
* set_change_info - set up the change_info4 for a reply
* @cinfo: pointer to nfsd4_change_info to be populated
* @fhp: pointer to svc_fh to use as source
*
* Many operations in NFSv4 require change_info4 in the reply. This function
* populates that from the info that we (should!) have already collected. In
* the event that we didn't get any pre-attrs, just zero out both.
*/
static void
set_change_info(struct nfsd4_change_info *cinfo, struct svc_fh *fhp)
{
cinfo->atomic = (u32)(fhp->fh_pre_saved && fhp->fh_post_saved && !fhp->fh_no_atomic_attr);
cinfo->before_change = fhp->fh_pre_change;
cinfo->after_change = fhp->fh_post_change;
/*
* If fetching the pre-change attributes failed, then we should
* have already failed the whole operation. We could have still
* failed to fetch post-change attributes however.
*
* If we didn't get post-op attrs, just zero-out the after
* field since we don't know what it should be. If the pre_saved
* field isn't set for some reason, throw warning and just copy
* whatever is in the after field.
*/
if (WARN_ON_ONCE(!fhp->fh_pre_saved))
cinfo->before_change = 0;
if (!fhp->fh_post_saved)
cinfo->after_change = 0;
}
static __be32
do_open_lookup(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfsd4_open *open, struct svc_fh **resfh)
{

11
fs/nfsd/xdr4.h
View File

@ -774,17 +774,6 @@ void warn_on_nonidempotent_op(struct nfsd4_op *op);
#define NFS4_SVC_XDRSIZE sizeof(struct nfsd4_compoundargs)
static inline void
set_change_info(struct nfsd4_change_info *cinfo, struct svc_fh *fhp)
{
BUG_ON(!fhp->fh_pre_saved);
cinfo->atomic = (u32)(fhp->fh_post_saved && !fhp->fh_no_atomic_attr);
cinfo->before_change = fhp->fh_pre_change;
cinfo->after_change = fhp->fh_post_change;
}
bool nfsd4_mach_creds_match(struct nfs4_client *cl, struct svc_rqst *rqstp);
bool nfs4svc_decode_compoundargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
bool nfs4svc_encode_compoundres(struct svc_rqst *rqstp, struct xdr_stream *xdr);