2022-11-28 19:31:49

by George Kennedy

Subject: [PATCH] VMCI: check context->notify_page after call to get_user_pages_fast() to avoid GPF

The call to get_user_pages_fast() in vmci_host_setup_notify() can return
NULL context->notify_page causing a GPF. To avoid GPF check if
context->notify_page == NULL and return error if so.

general protection fault, probably for non-canonical address
0xe0009d1000000060: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: maybe wild-memory-access in range [0x0005088000000300-
0x0005088000000307]
CPU: 2 PID: 26180 Comm: repro_34802241 Not tainted 6.1.0-rc4 #1
Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0 04/01/2014
RIP: 0010:vmci_ctx_check_signal_notify+0x91/0xe0
Call Trace:
<TASK>
vmci_host_unlocked_ioctl+0x362/0x1f40
__x64_sys_ioctl+0x1a1/0x230
do_syscall_64+0x3a/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: a1d88436d53a ("VMCI: Fix two UVA mapping bugs")
Reported-by: syzkaller <[email protected]>
Signed-off-by: George Kennedy <[email protected]>
---
drivers/misc/vmw_vmci/vmci_host.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/misc/vmw_vmci/vmci_host.c b/drivers/misc/vmw_vmci/vmci_host.c
index da1e2a773823..857b9851402a 100644
--- a/drivers/misc/vmw_vmci/vmci_host.c
+++ b/drivers/misc/vmw_vmci/vmci_host.c
@@ -242,6 +242,8 @@ static int vmci_host_setup_notify(struct vmci_ctx *context,
context->notify_page = NULL;
return VMCI_ERROR_GENERIC;
}
+ if (context->notify_page == NULL)
+ return VMCI_ERROR_UNAVAILABLE;

/*
* Map the locked page and set up notify pointer.
--
2.31.1

2022-11-29 22:39:50

by Vishnu Dasa

Subject: Re: [PATCH] VMCI: check context->notify_page after call to get_user_pages_fast() to avoid GPF

> On Nov 28, 2022, at 12:18 PM, George Kennedy <[email protected]> wrote:
>
> The call to get_user_pages_fast() in vmci_host_setup_notify() can return
> NULL context->notify_page causing a GPF. To avoid GPF check if
> context->notify_page == NULL and return error if so.
>
> general protection fault, probably for non-canonical address
> 0xe0009d1000000060: 0000 [#1] PREEMPT SMP KASAN NOPTI
> KASAN: maybe wild-memory-access in range [0x0005088000000300-
> 0x0005088000000307]
> CPU: 2 PID: 26180 Comm: repro_34802241 Not tainted 6.1.0-rc4 #1
> Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0 04/01/2014
> RIP: 0010:vmci_ctx_check_signal_notify+0x91/0xe0
> Call Trace:
> <TASK>
> vmci_host_unlocked_ioctl+0x362/0x1f40
> __x64_sys_ioctl+0x1a1/0x230
> do_syscall_64+0x3a/0x90
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> Fixes: a1d88436d53a ("VMCI: Fix two UVA mapping bugs")
> Reported-by: syzkaller <[email protected]>
> Signed-off-by: George Kennedy <[email protected]>

Thanks for the fix!

Reviewed-by: Vishnu Dasa <[email protected]>

> ---
> drivers/misc/vmw_vmci/vmci_host.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/misc/vmw_vmci/vmci_host.c b/drivers/misc/vmw_vmci/vmci_host.c
> index da1e2a773823..857b9851402a 100644
> --- a/drivers/misc/vmw_vmci/vmci_host.c
> +++ b/drivers/misc/vmw_vmci/vmci_host.c
> @@ -242,6 +242,8 @@ static int vmci_host_setup_notify(struct vmci_ctx *context,
> context->notify_page = NULL;
> return VMCI_ERROR_GENERIC;
> }
> + if (context->notify_page == NULL)
> + return VMCI_ERROR_UNAVAILABLE;
>
> /*
> * Map the locked page and set up notify pointer.
> --
> 2.31.1
>