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authorGustavo A. R. Silva <gustavo@embeddedor.com>2019-01-09 16:05:10 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-01-22 13:34:35 +0100
commitd7ac3c6ef5d8ce14b6381d52eb7adafdd6c8bb3c (patch)
tree80f36428f5a486c7256dbbd2f742dd1e4fbea929
parenthpet: Fix missing '=' character in the __setup() code of hpet_mmap_enable (diff)
downloadlinux-dev-d7ac3c6ef5d8ce14b6381d52eb7adafdd6c8bb3c.tar.xz
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applicom: Fix potential Spectre v1 vulnerabilities
IndexCard 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/applicom.c:418 ac_write() warn: potential spectre issue 'apbs' [r] drivers/char/applicom.c:728 ac_ioctl() warn: potential spectre issue 'apbs' [r] (local cap) Fix this by sanitizing IndexCard before using it to index apbs. 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://lore.kernel.org/lkml/20180423164740.GY17484@dhcp22.suse.cz/ Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/char/applicom.c35
1 files changed, 24 insertions, 11 deletions
diff --git a/drivers/char/applicom.c b/drivers/char/applicom.c
index c0a5b1f3a986..4ccc39e00ced 100644
--- a/drivers/char/applicom.c
+++ b/drivers/char/applicom.c
@@ -32,6 +32,7 @@
#include <linux/wait.h>
#include <linux/init.h>
#include <linux/fs.h>
+#include <linux/nospec.h>
#include <asm/io.h>
#include <linux/uaccess.h>
@@ -386,7 +387,11 @@ static ssize_t ac_write(struct file *file, const char __user *buf, size_t count,
TicCard = st_loc.tic_des_from_pc; /* tic number to send */
IndexCard = NumCard - 1;
- if((NumCard < 1) || (NumCard > MAX_BOARD) || !apbs[IndexCard].RamIO)
+ if (IndexCard >= MAX_BOARD)
+ return -EINVAL;
+ IndexCard = array_index_nospec(IndexCard, MAX_BOARD);
+
+ if (!apbs[IndexCard].RamIO)
return -EINVAL;
#ifdef DEBUG
@@ -697,6 +702,7 @@ static long ac_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
unsigned char IndexCard;
void __iomem *pmem;
int ret = 0;
+ static int warncount = 10;
volatile unsigned char byte_reset_it;
struct st_ram_io *adgl;
void __user *argp = (void __user *)arg;
@@ -711,16 +717,12 @@ static long ac_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
mutex_lock(&ac_mutex);
IndexCard = adgl->num_card-1;
- if(cmd != 6 && ((IndexCard >= MAX_BOARD) || !apbs[IndexCard].RamIO)) {
- static int warncount = 10;
- if (warncount) {
- printk( KERN_WARNING "APPLICOM driver IOCTL, bad board number %d\n",(int)IndexCard+1);
- warncount--;
- }
- kfree(adgl);
- mutex_unlock(&ac_mutex);
- return -EINVAL;
- }
+ if (cmd != 6 && IndexCard >= MAX_BOARD)
+ goto err;
+ IndexCard = array_index_nospec(IndexCard, MAX_BOARD);
+
+ if (cmd != 6 && !apbs[IndexCard].RamIO)
+ goto err;
switch (cmd) {
@@ -838,5 +840,16 @@ static long ac_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
kfree(adgl);
mutex_unlock(&ac_mutex);
return 0;
+
+err:
+ if (warncount) {
+ pr_warn("APPLICOM driver IOCTL, bad board number %d\n",
+ (int)IndexCard + 1);
+ warncount--;
+ }
+ kfree(adgl);
+ mutex_unlock(&ac_mutex);
+ return -EINVAL;
+
}