From: Chuck Lever Date: Mon, 1 Dec 2025 22:09:55 +0000 (-0500) Subject: nfsd: fix nfsd_file reference leak in nfsd4_add_rdaccess_to_wrdeleg() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8072e34e1387d03102b788677d491e2bcceef6f5;p=thirdparty%2Fkernel%2Fstable.git nfsd: fix nfsd_file reference leak in nfsd4_add_rdaccess_to_wrdeleg() nfsd4_add_rdaccess_to_wrdeleg() unconditionally overwrites fp->fi_fds[O_RDONLY] with a newly acquired nfsd_file. However, if the client already has a SHARE_ACCESS_READ open from a previous OPEN operation, this action overwrites the existing pointer without releasing its reference, orphaning the previous reference. Additionally, the function originally stored the same nfsd_file pointer in both fp->fi_fds[O_RDONLY] and fp->fi_rdeleg_file with only a single reference. When put_deleg_file() runs, it clears fi_rdeleg_file and calls nfs4_file_put_access() to release the file. However, nfs4_file_put_access() only releases fi_fds[O_RDONLY] when the fi_access[O_RDONLY] counter drops to zero. If another READ open exists on the file, the counter remains elevated and the nfsd_file reference from the delegation is never released. This potentially causes open conflicts on that file. Then, on server shutdown, these leaks cause __nfsd_file_cache_purge() to encounter files with an elevated reference count that cannot be cleaned up, ultimately triggering a BUG() in kmem_cache_destroy() because there are still nfsd_file objects allocated in that cache. Fixes: e7a8ebc305f2 ("NFSD: Offer write delegation for OPEN with OPEN4_SHARE_ACCESS_WRITE") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 35004568d43e..11877b96dc4c 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1218,8 +1218,10 @@ static void put_deleg_file(struct nfs4_file *fp) if (nf) nfsd_file_put(nf); - if (rnf) + if (rnf) { + nfsd_file_put(rnf); nfs4_file_put_access(fp, NFS4_SHARE_ACCESS_READ); + } } static void nfsd4_finalize_deleg_timestamps(struct nfs4_delegation *dp, struct file *f) @@ -6231,10 +6233,14 @@ nfsd4_add_rdaccess_to_wrdeleg(struct svc_rqst *rqstp, struct nfsd4_open *open, fp = stp->st_stid.sc_file; spin_lock(&fp->fi_lock); __nfs4_file_get_access(fp, NFS4_SHARE_ACCESS_READ); - fp = stp->st_stid.sc_file; - fp->fi_fds[O_RDONLY] = nf; - fp->fi_rdeleg_file = nf; + if (!fp->fi_fds[O_RDONLY]) { + fp->fi_fds[O_RDONLY] = nf; + nf = NULL; + } + fp->fi_rdeleg_file = nfsd_file_get(fp->fi_fds[O_RDONLY]); spin_unlock(&fp->fi_lock); + if (nf) + nfsd_file_put(nf); } return true; }