This is a note to let you know that I've just added the patch titled
NFSD: Fix potential use-after-free in nfsd_file_put()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-fix-potential-use-after-free-in-nfsd_file_put.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 2214602127874e0af303cd41df4e9e6c155f9430
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Tue May 31 19:49:01 2022 -0400
NFSD: Fix potential use-after-free in nfsd_file_put()
[ Upstream commit b6c71c66b0ad8f2b59d9bc08c7a5079b110bec01 ]
nfsd_file_put_noref() can free @nf, so don't dereference @nf
immediately upon return from nfsd_file_put_noref().
Suggested-by: Trond Myklebust <trondmy@xxxxxxxxxxxxxxx>
Fixes: 999397926ab3 ("nfsd: Clean up nfsd_file_put()")
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 27952e2f3aa14..1d3d13b78be0e 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -302,11 +302,12 @@ nfsd_file_put(struct nfsd_file *nf)
if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags) == 0) {
nfsd_file_flush(nf);
nfsd_file_put_noref(nf);
- } else {
+ } else if (nf->nf_file) {
nfsd_file_put_noref(nf);
- if (nf->nf_file)
- nfsd_file_schedule_laundrette();
- }
+ nfsd_file_schedule_laundrette();
+ } else
+ nfsd_file_put_noref(nf);
+
if (atomic_long_read(&nfsd_filecache_count) >= NFSD_FILE_LRU_LIMIT)
nfsd_file_gc();
}
