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[129.94.175.166]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2e92fa36672sm1683676a91.14.2024.10.30.06.24.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Oct 2024 06:24:40 -0700 (PDT) From: Tuo Li To: ayush.sawal@chelsio.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, almasrymina@google.com, dtatulea@nvidia.com, jacob.e.keller@intel.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, Tuo Li Subject: [PATCH] chcr_ktls: fix a possible null-pointer dereference in chcr_ktls_dev_add() Date: Thu, 31 Oct 2024 00:23:52 +1100 Message-ID: <20241030132352.154488-1-islituo@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" There is a possible null-pointer dereference related to the wait-completion synchronization mechanism in the function chcr_ktls_dev_add(). Consider the following execution scenario: chcr_ktls_cpl_act_open_rpl() //641 u_ctx =3D adap->uld[CXGB4_ULD_KTLS].handle; //686 if (u_ctx) { //687 complete(&tx_info->completion); //704 The variable u_ctx is checked by an if statement at Line 687, which means it can be NULL. Then, complete() is called at Line 704, which will wake up wait_for_completion_xxx(). Consider the wait_for_completion_timeout() in chcr_ktls_dev_add(): chcr_ktls_dev_add() //412 u_ctx =3D adap->uld[CXGB4_ULD_KTLS].handle; //432 wait_for_completion_timeout(&tx_info->completion, 30 * HZ); //551 xa_erase(&u_ctx->tid_list, tx_info->tid); //580 The variable u_ctx is dereferenced without being rechecked at Line 580 after the wait_for_completion_timeout(), which can introduce a null-pointer dereference. Besides, the variable u_ctx is also checked at Line 442 in chcr_ktls_dev_add(), which indicates that u_ctx is likely to be NULL in some execution contexts. To fix this possible null-pointer dereference, a NULL check is put ahead of the call to xa_erase(). This potential bug was discovered using an experimental static analysis tool developed by our team. The tool deduces complete() and wait_for_completion() pairs using alias analysis. It then applies data flow analysis to detect null-pointer dereferences across synchronization points. Fixes: 65e302a9bd57 ("cxgb4/ch_ktls: Clear resources when pf4 device is rem= oved")=20 Signed-off-by: Tuo Li --- drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c= b/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c index e8e460a92e0e..524c8e032bc8 100644 --- a/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c +++ b/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c @@ -577,7 +577,8 @@ static int chcr_ktls_dev_add(struct net_device *netdev,= struct sock *sk, cxgb4_remove_tid(&tx_info->adap->tids, tx_info->tx_chan, tx_info->tid, tx_info->ip_family); =20 - xa_erase(&u_ctx->tid_list, tx_info->tid); + if (u_ctx) + xa_erase(&u_ctx->tid_list, tx_info->tid); =20 put_module: /* release module refcount */ --=20 2.43.0