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nfsd: fix oops on access from high-numbered ports

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This bug was always here, but before my commit 6fa02839bf
("recheck for secure ports in fh_verify"), it could only be triggered by
failure of a kmalloc().  After that commit it could be triggered by a
client making a request from a non-reserved port for access to an export
marked "secure".  (Exports are "secure" by default.)

The result is a struct svc_export with a reference count one too low,
resulting in likely oopses next time the export is accessed.

The reference counting here is not straightforward; a later patch will
clean up fh_verify().

Thanks to Lukas Hejtmanek for the bug report and followup.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Lukas Hejtmanek <xhejtman@ics.muni.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
J. Bruce Fields 2008-03-14 19:37:11 -04:00 committed by Linus Torvalds
parent 9b89ca7a38
commit b663c6fd98
1 changed files with 2 additions and 2 deletions
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4
fs/nfsd/nfsfh.c
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@ -232,6 +232,7 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
fhp->fh_dentry = dentry;
fhp->fh_export = exp;
nfsd_nr_verified++;
cache_get(&exp->h);
} else {
/*
* just rechecking permissions
@ -241,6 +242,7 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
dprintk("nfsd: fh_verify - just checking\n");
dentry = fhp->fh_dentry;
exp = fhp->fh_export;
cache_get(&exp->h);
/*
* Set user creds for this exportpoint; necessary even
* in the "just checking" case because this may be a
@ -252,8 +254,6 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
if (error)
goto out;
}
cache_get(&exp->h);
error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
if (error)