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| author | J. Bruce Fields <bfields@citi.umich.edu> | 2009-05-05 19:04:29 -0400 |
|---|---|---|
| committer | J. Bruce Fields <bfields@citi.umich.edu> | 2009-05-06 16:16:36 -0400 |
| commit | b2c0cea6b1cb210e962f07047df602875564069e (patch) | |
| tree | f6327b45df075955d8ef9e9ad93c453ea5fc7a4c /fs/nfsd | |
| parent | ccecee1e5e42981f5eb37f4411e8552b9db04d30 (diff) | |
| download | linux-b2c0cea6b1cb210e962f07047df602875564069e.tar.bz2 | |
nfsd4: check for negative dentry before use in nfsv4 readdir
After 2f9092e1020246168b1309b35e085ecd7ff9ff72 "Fix i_mutex vs. readdir
handling in nfsd" (and 14f7dd63 "Copy XFS readdir hack into nfsd code"),
an entry may be removed between the first mutex_unlock and the second
mutex_lock. In this case, lookup_one_len() will return a negative
dentry. Check for this case to avoid a NULL dereference.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Reviewed-by: J. R. Okajima <hooanon05@yahoo.co.jp>
Cc: stable@kernel.org
Diffstat (limited to 'fs/nfsd')
| -rw-r--r-- | fs/nfsd/nfs4xdr.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index b820c311931c..b73549d293be 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -2214,6 +2214,15 @@ nfsd4_encode_dirent_fattr(struct nfsd4_readdir *cd, dentry = lookup_one_len(name, cd->rd_fhp->fh_dentry, namlen); if (IS_ERR(dentry)) return nfserrno(PTR_ERR(dentry)); + if (!dentry->d_inode) { + /* + * nfsd_buffered_readdir drops the i_mutex between + * readdir and calling this callback, leaving a window + * where this directory entry could have gone away. + */ + dput(dentry); + return nfserr_noent; + } exp_get(exp); /* @@ -2276,6 +2285,7 @@ nfsd4_encode_dirent(void *ccdv, const char *name, int namlen, struct nfsd4_readdir *cd = container_of(ccd, struct nfsd4_readdir, common); int buflen; __be32 *p = cd->buffer; + __be32 *cookiep; __be32 nfserr = nfserr_toosmall; /* In nfsv4, "." and ".." never make it onto the wire.. */ @@ -2292,7 +2302,7 @@ nfsd4_encode_dirent(void *ccdv, const char *name, int namlen, goto fail; *p++ = xdr_one; /* mark entry present */ - cd->offset = p; /* remember pointer */ + cookiep = p; p = xdr_encode_hyper(p, NFS_OFFSET_MAX); /* offset of next entry */ p = xdr_encode_array(p, name, namlen); /* name length & name */ @@ -2306,6 +2316,8 @@ nfsd4_encode_dirent(void *ccdv, const char *name, int namlen, goto fail; case nfserr_dropit: goto fail; + case nfserr_noent: + goto skip_entry; default: /* * If the client requested the RDATTR_ERROR attribute, @@ -2324,6 +2336,8 @@ nfsd4_encode_dirent(void *ccdv, const char *name, int namlen, } cd->buflen -= (p - cd->buffer); cd->buffer = p; + cd->offset = cookiep; +skip_entry: cd->common.err = nfs_ok; return 0; fail: |