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[2.37.205.63]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48a77aeb47csm51114445e9.1.2026.04.28.06.42.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Apr 2026 06:42:39 -0700 (PDT) From: Alessandro Zanni To: chuck.lever@oracle.com, jlayton@kernel.org, neil@brown.name, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com, trondmy@kernel.org, anna@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org Cc: Alessandro Zanni , linux-nfs@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+60cfa08822470bbebe44@syzkaller.appspotmail.com Subject: [PATCH] net: sunrpc: fix slab-out-of-bounds read in cache_seq_start_rcu Date: Tue, 28 Apr 2026 15:42:24 +0200 Message-ID: <20260428134230.136533-1-alessandro.zanni87@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Syzbot reported slab-out-of-bounds read in cache_seq_start_rcu(). The issue happens in function __cache_seq_start() when is invoked hlist_for_each_entry_rcu() and the hash value is greater than the hash_size. This fix verifies that the hash index is within the hash_size value before dereferencing the hash table: if the hash index is out of bounds return NULL, otherwise access the value. Fixes: ae74136b4bb6 ("SUNRPC: Allow cache lookups to use RCU protection rather than the r/w spinlock") Reported-by: syzbot+60cfa08822470bbebe44@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=60cfa08822470bbebe44 Signed-off-by: Alessandro Zanni --- net/sunrpc/cache.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 7081c1214e6c..aac5f03112f5 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -1348,6 +1348,9 @@ static void *__cache_seq_start(struct seq_file *m, loff_t *pos) hash = n >> 32; entry = n & ((1LL<<32) - 1); + if (hash >= cd->hash_size) + return NULL; + hlist_for_each_entry_rcu(ch, &cd->hash_table[hash], cache_list) if (!entry--) return ch; -- 2.47.3