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| author | Andrea Parri (Microsoft) <parri.andrea@gmail.com> | 2020-12-09 10:08:26 +0300 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2021-02-05 12:55:42 +0300 |
| commit | e4d221b42354b2e2ddb9187a806afb651eee2cda (patch) | |
| tree | ed8fb74205a96a8ca8c94eaccb1c8e2eec4ac5db | |
| parent | e3fa4b747f085d2cda09bba0533b86fa76038635 (diff) | |
| download | linux-e4d221b42354b2e2ddb9187a806afb651eee2cda.tar.xz | |
Drivers: hv: vmbus: Resolve race condition in vmbus_onoffer_rescind()
An erroneous or malicious host could send multiple rescind messages for
a same channel. In vmbus_onoffer_rescind(), the guest maps the channel
ID to obtain a pointer to the channel object and it eventually releases
such object and associated data. The host could time rescind messages
and lead to an use-after-free. Add a new flag to the channel structure
to make sure that only one instance of vmbus_onoffer_rescind() can get
the reference to the channel object.
Reported-by: Juan Vazquez <juvazq@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20201209070827.29335-6-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
| -rw-r--r-- | drivers/hv/channel_mgmt.c | 12 | ||||
| -rw-r--r-- | include/linux/hyperv.h | 1 |
2 files changed, 13 insertions, 0 deletions
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 4072fd1f2214..68950a1e4b63 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -1063,6 +1063,18 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) mutex_lock(&vmbus_connection.channel_mutex); channel = relid2channel(rescind->child_relid); + if (channel != NULL) { + /* + * Guarantee that no other instance of vmbus_onoffer_rescind() + * has got a reference to the channel object. Synchronize on + * &vmbus_connection.channel_mutex. + */ + if (channel->rescind_ref) { + mutex_unlock(&vmbus_connection.channel_mutex); + return; + } + channel->rescind_ref = true; + } mutex_unlock(&vmbus_connection.channel_mutex); if (channel == NULL) { diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index 2ea967bc17ad..f0d48a368f13 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -809,6 +809,7 @@ struct vmbus_channel { u8 monitor_bit; bool rescind; /* got rescind msg */ + bool rescind_ref; /* got rescind msg, got channel reference */ struct completion rescind_event; u32 ringbuffer_gpadlhandle; |