From 701956d4018e5d5438570e39e8bda47edd32c489 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Wed, 9 Jan 2019 13:02:36 -0600 Subject: [PATCH] char/mwave: fix potential Spectre v1 vulnerability ipcnum is indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/char/mwave/mwavedd.c:299 mwave_ioctl() warn: potential spectre issue 'pDrvData->IPCs' [w] (local cap) Fix this by sanitizing ipcnum before using it to index pDrvData->IPCs. Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva Signed-off-by: Greg Kroah-Hartman --- drivers/char/mwave/mwavedd.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/char/mwave/mwavedd.c b/drivers/char/mwave/mwavedd.c index b5e3103c1175..e43c876a9223 100644 --- a/drivers/char/mwave/mwavedd.c +++ b/drivers/char/mwave/mwavedd.c @@ -59,6 +59,7 @@ #include #include #include +#include #include "smapi.h" #include "mwavedd.h" #include "3780i.h" @@ -289,6 +290,8 @@ static long mwave_ioctl(struct file *file, unsigned int iocmd, ipcnum); return -EINVAL; } + ipcnum = array_index_nospec(ipcnum, + ARRAY_SIZE(pDrvData->IPCs)); PRINTK_3(TRACE_MWAVE, "mwavedd::mwave_ioctl IOCTL_MW_REGISTER_IPC" " ipcnum %x entry usIntCount %x\n", @@ -317,6 +320,8 @@ static long mwave_ioctl(struct file *file, unsigned int iocmd, " Invalid ipcnum %x\n", ipcnum); return -EINVAL; } + ipcnum = array_index_nospec(ipcnum, + ARRAY_SIZE(pDrvData->IPCs)); PRINTK_3(TRACE_MWAVE, "mwavedd::mwave_ioctl IOCTL_MW_GET_IPC" " ipcnum %x, usIntCount %x\n", @@ -383,6 +388,8 @@ static long mwave_ioctl(struct file *file, unsigned int iocmd, ipcnum); return -EINVAL; } + ipcnum = array_index_nospec(ipcnum, + ARRAY_SIZE(pDrvData->IPCs)); mutex_lock(&mwave_mutex); if (pDrvData->IPCs[ipcnum].bIsEnabled == true) { pDrvData->IPCs[ipcnum].bIsEnabled = false;