* [PATCH AUTOSEL 4.19 21/26] Drivers: hv: vmbus: Resolve race condition in vmbus_onoffer_rescind() [not found] <20210224125435.483539-1-sashal@kernel.org> @ 2021-02-24 12:54 ` Sasha Levin 2021-02-24 13:21 ` Andrea Parri 0 siblings, 1 reply; 2+ messages in thread From: Sasha Levin @ 2021-02-24 12:54 UTC (permalink / raw) To: linux-kernel, stable Cc: Andrea Parri (Microsoft), Juan Vazquez, Michael Kelley, Wei Liu, Sasha Levin, linux-hyperv From: "Andrea Parri (Microsoft)" <parri.andrea@gmail.com> [ Upstream commit e4d221b42354b2e2ddb9187a806afb651eee2cda ] 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> Signed-off-by: Sasha Levin <sashal@kernel.org> --- drivers/hv/channel_mgmt.c | 12 ++++++++++++ include/linux/hyperv.h | 1 + 2 files changed, 13 insertions(+) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 7920b0d7e35a7..1322e799938af 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -954,6 +954,18 @@ 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 35461d49d3aee..59525fe25abde 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -736,6 +736,7 @@ 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; -- 2.27.0 ^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH AUTOSEL 4.19 21/26] Drivers: hv: vmbus: Resolve race condition in vmbus_onoffer_rescind() 2021-02-24 12:54 ` [PATCH AUTOSEL 4.19 21/26] Drivers: hv: vmbus: Resolve race condition in vmbus_onoffer_rescind() Sasha Levin @ 2021-02-24 13:21 ` Andrea Parri 0 siblings, 0 replies; 2+ messages in thread From: Andrea Parri @ 2021-02-24 13:21 UTC (permalink / raw) To: Sasha Levin Cc: linux-kernel, stable, Juan Vazquez, Michael Kelley, Wei Liu, linux-hyperv On Wed, Feb 24, 2021 at 07:54:29AM -0500, Sasha Levin wrote: > From: "Andrea Parri (Microsoft)" <parri.andrea@gmail.com> > > [ Upstream commit e4d221b42354b2e2ddb9187a806afb651eee2cda ] > > 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> > Signed-off-by: Sasha Levin <sashal@kernel.org> Same here. Andrea > --- > drivers/hv/channel_mgmt.c | 12 ++++++++++++ > include/linux/hyperv.h | 1 + > 2 files changed, 13 insertions(+) > > diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c > index 7920b0d7e35a7..1322e799938af 100644 > --- a/drivers/hv/channel_mgmt.c > +++ b/drivers/hv/channel_mgmt.c > @@ -954,6 +954,18 @@ 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 35461d49d3aee..59525fe25abde 100644 > --- a/include/linux/hyperv.h > +++ b/include/linux/hyperv.h > @@ -736,6 +736,7 @@ 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; > -- > 2.27.0 > ^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-02-24 12:54 ` [PATCH AUTOSEL 4.19 21/26] Drivers: hv: vmbus: Resolve race condition in vmbus_onoffer_rescind() Sasha Levin
2021-02-24 13:21 ` Andrea Parri
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