From: Maxim Mikityanskiy maximmi@nvidia.com
mainline inclusion from mainline-v5.18-rc7 commit 3740651bf7e200109dd42d5b2fb22226b26f960a category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I990AF CVE: CVE-2021-47131
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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The commit cited below claims to fix a use-after-free condition after tls_device_down. Apparently, the description wasn't fully accurate. The context stayed alive, but ctx->netdev became NULL, and the offload was torn down without a proper fallback, so a bug was present, but a different kind of bug.
Due to misunderstanding of the issue, the original patch dropped the refcount_dec_and_test line for the context to avoid the alleged premature deallocation. That line has to be restored, because it matches the refcount_inc_not_zero from the same function, otherwise the contexts that survived tls_device_down are leaked.
This patch fixes the described issue by restoring refcount_dec_and_test. After this change, there is no leak anymore, and the fallback to software kTLS still works.
Fixes: c55dcdd435aa ("net/tls: Fix use-after-free after the TLS device goes down and up") Signed-off-by: Maxim Mikityanskiy maximmi@nvidia.com Reviewed-by: Tariq Toukan tariqt@nvidia.com Link: https://lore.kernel.org/r/20220512091830.678684-1-maximmi@nvidia.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Ziyang Xuan william.xuanziyang@huawei.com --- net/tls/tls_device.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c index 70f53b5f444cd..524a16fdcadf6 100644 --- a/net/tls/tls_device.c +++ b/net/tls/tls_device.c @@ -1037,7 +1037,10 @@ static int tls_device_down(struct net_device *netdev)
/* Device contexts for RX and TX will be freed in on sk_destruct * by tls_device_free_ctx. rx_conf and tx_conf stay in TLS_HW. + * Now release the ref taken above. */ + if (refcount_dec_and_test(&ctx->refcount)) + tls_device_free_ctx(ctx); }
up_write(&device_offload_lock);