lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <20aed7c604115c7f346cdbbe848c37feded3cf21.camel@redhat.com> Date: Tue, 17 Oct 2023 12:31:36 +0200 From: Paolo Abeni <pabeni@...hat.com> To: Juntong Deng <juntong.deng@...look.com>, borisp@...dia.com, john.fastabend@...il.com, kuba@...nel.org, davem@...emloft.net, edumazet@...gle.com Cc: netdev@...r.kernel.org, linux-kernel-mentees@...ts.linuxfoundation.org, linux-kernel@...r.kernel.org, syzbot+29c22ea2d6b2c5fd2eae@...kaller.appspotmail.com Subject: Re: [PATCH] net/tls: Fix slab-use-after-free in tls_encrypt_done On Thu, 2023-10-12 at 19:02 +0800, Juntong Deng wrote: > In the current implementation, ctx->async_wait.completion is completed > after spin_lock_bh, which causes tls_sw_release_resources_tx to > continue executing and return to tls_sk_proto_cleanup, then return > to tls_sk_proto_close, and after that enter tls_sw_free_ctx_tx to kfree > the entire struct tls_context (including ctx->encrypt_compl_lock). > > Since ctx->encrypt_compl_lock has been freed, subsequent spin_unlock_bh > will result in slab-use-after-free error. Due to SMP, even using > spin_lock_bh does not prevent tls_sw_release_resources_tx from continuing > on other CPUs. After tls_sw_release_resources_tx is woken up, there is no > attempt to hold ctx->encrypt_compl_lock again, therefore everything > described above is possible. > > The fix is to put complete(&ctx->async_wait.completion) after > spin_unlock_bh, making the release after the unlock. Since complete is > only executed if pending is 0, which means this is the last record, there > is no need to worry about race condition causing duplicate completes. > > Reported-by: syzbot+29c22ea2d6b2c5fd2eae@...kaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=29c22ea2d6b2c5fd2eae > Signed-off-by: Juntong Deng <juntong.deng@...look.com> Have you tested this patch vs the syzbot reproducer? I think the following race is still present: CPU0 CPU1 tls_sw_release_resources_tx tls_encrypt_done spin_lock_bh spin_unlock_bh spin_lock_bh spin_unlock_bh complete wait // ... tls_sk_proto_close test_and_set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask // UaF regardless of 'complete()' being invoked before or after the 'spin_unlock_bh()'. Paolo
Powered by blists - more mailing lists