From: Xiaomeng Tong <xiam0nd.tong@gmail.com>
To: gregkh@linuxfoundation.org, jirislaby@kernel.org
Cc: linux-kernel@vger.kernel.org, Xiaomeng Tong <xiam0nd.tong@gmail.com>
Subject: [PATCH v2] vt_ioctl: fix potential spectre v1 in VT_DISALLOCATE
Date: Tue, 22 Feb 2022 16:11:01 +0800 [thread overview]
Message-ID: <20220222081101.21233-1-xiam0nd.tong@gmail.com> (raw)
In VT_ACTIVATE an almost identical code path has been patched
with array_index_nospec. In the VT_DISALLOCATE path, the arg is
the user input from a system call argument and lately used as a index
for vc_cons[index].d access, which can be reached through path like
vt_disallocate->vc_busy or vt_disallocate->vc_deallocate.
For consistency both code paths should have the same mitigations
applied. Also, the code style is adjusted as suggested by Jiri.
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
---
drivers/tty/vt/vt_ioctl.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index 580136986..8c685b501 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -898,11 +898,13 @@ int vt_ioctl(struct tty_struct *tty,
if (arg > MAX_NR_CONSOLES)
return -ENXIO;
- if (arg == 0)
+ if (arg == 0) {
vt_disallocate_all();
- else
- return vt_disallocate(--arg);
- break;
+ break;
+ }
+
+ arg = array_index_nospec(arg - 1, MAX_NR_CONSOLES);
+ return vt_disallocate(arg);
case VT_RESIZE:
{
--
2.17.1
reply other threads:[~2022-02-22 8:11 UTC|newest]
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