Messages in this thread Patch in this message |  | | From | Li Lingfeng <> | | Subject | [PATCH] nfsd: free nfsd_file by gc after adding it to lru list | | Date | Mon, 13 Jan 2025 10:59:57 +0800 |
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In nfsd_file_put, after inserting the nfsd_file into the nfsd_file_lru list, gc may be triggered in another thread and immediately release this nfsd_file, which will lead to a UAF when accessing this nfsd_file again.
All the places where unhash is done will also perform lru_remove, so there is no need to do lru_remove separately here. After inserting the nfsd_file into the nfsd_file_lru list, it can be released by relying on gc.
Fixes: 4a0e73e635e3 ("NFSD: Leave open files out of the filecache LRU") Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- fs/nfsd/filecache.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-)
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index a1cdba42c4fa..37b65cb1579a 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -372,18 +372,10 @@ nfsd_file_put(struct nfsd_file *nf) /* Try to add it to the LRU. If that fails, decrement. */ if (nfsd_file_lru_add(nf)) { /* If it's still hashed, we're done */ - if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { + if (list_lru_count(&nfsd_file_lru)) nfsd_file_schedule_laundrette(); - return; - } - /* - * We're racing with unhashing, so try to remove it from - * the LRU. If removal fails, then someone else already - * has our reference. - */ - if (!nfsd_file_lru_remove(nf)) - return; + return; } } if (refcount_dec_and_test(&nf->nf_ref)) -- 2.31.1
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