* [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
@ 2017-03-22 14:01 Colin King
2017-03-22 19:39 ` Dan Carpenter
0 siblings, 1 reply; 4+ messages in thread
From: Colin King @ 2017-03-22 14:01 UTC (permalink / raw)
To: Johannes Thumshirn, James E . J . Bottomley, Martin K . Petersen,
fcoe-devel, linux-scsi
Cc: kernel-janitors, linux-kernel
From: Colin Ian King <colin.king@canonical.com>
Reading and writing to mode[count - 1] implies the count should not
be less than 1 so add a sanity check for this.
Detected with CoverityScan, CID#1357345 ("Overflowed array index write")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
drivers/scsi/fcoe/fcoe_sysfs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/scsi/fcoe/fcoe_sysfs.c b/drivers/scsi/fcoe/fcoe_sysfs.c
index 9cf3d56296ab..e298240c728c 100644
--- a/drivers/scsi/fcoe/fcoe_sysfs.c
+++ b/drivers/scsi/fcoe/fcoe_sysfs.c
@@ -288,7 +288,7 @@ static ssize_t store_ctlr_mode(struct device *dev,
struct fcoe_ctlr_device *ctlr = dev_to_ctlr(dev);
char mode[FCOE_MAX_MODENAME_LEN + 1];
- if (count > FCOE_MAX_MODENAME_LEN)
+ if (count < 1 || count > FCOE_MAX_MODENAME_LEN)
return -EINVAL;
strncpy(mode, buf, count);
--
2.11.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
2017-03-22 14:01 [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option Colin King
@ 2017-03-22 19:39 ` Dan Carpenter
2017-03-22 19:42 ` Colin Ian King
0 siblings, 1 reply; 4+ messages in thread
From: Dan Carpenter @ 2017-03-22 19:39 UTC (permalink / raw)
To: Colin King
Cc: Johannes Thumshirn, James E . J . Bottomley, Martin K . Petersen,
fcoe-devel, linux-scsi, kernel-janitors, linux-kernel
On Wed, Mar 22, 2017 at 02:01:37PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Reading and writing to mode[count - 1] implies the count should not
> be less than 1 so add a sanity check for this.
>
> Detected with CoverityScan, CID#1357345 ("Overflowed array index write")
>
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
This is harmless, of course, but count can't be zero. This is a sysfs
file so we test for zero size writes in sysfs_kf_write() and return
early.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
2017-03-22 19:39 ` Dan Carpenter
@ 2017-03-22 19:42 ` Colin Ian King
2017-03-23 11:45 ` Dan Carpenter
0 siblings, 1 reply; 4+ messages in thread
From: Colin Ian King @ 2017-03-22 19:42 UTC (permalink / raw)
To: Dan Carpenter
Cc: Johannes Thumshirn, James E . J . Bottomley, Martin K . Petersen,
fcoe-devel, linux-scsi, kernel-janitors, linux-kernel
On 22/03/17 19:39, Dan Carpenter wrote:
> On Wed, Mar 22, 2017 at 02:01:37PM +0000, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Reading and writing to mode[count - 1] implies the count should not
>> be less than 1 so add a sanity check for this.
>>
>> Detected with CoverityScan, CID#1357345 ("Overflowed array index write")
>>
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>
> This is harmless, of course, but count can't be zero. This is a sysfs
> file so we test for zero size writes in sysfs_kf_write() and return
> early.
Ah, thanks for pointing out that. I overlooked that detail.
Colin
>
> regards,
> dan carpenter
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
2017-03-22 19:42 ` Colin Ian King
@ 2017-03-23 11:45 ` Dan Carpenter
0 siblings, 0 replies; 4+ messages in thread
From: Dan Carpenter @ 2017-03-23 11:45 UTC (permalink / raw)
To: Colin Ian King
Cc: Johannes Thumshirn, James E . J . Bottomley, Martin K . Petersen,
fcoe-devel, linux-scsi, kernel-janitors, linux-kernel
On Wed, Mar 22, 2017 at 07:42:08PM +0000, Colin Ian King wrote:
> On 22/03/17 19:39, Dan Carpenter wrote:
> > On Wed, Mar 22, 2017 at 02:01:37PM +0000, Colin King wrote:
> >> From: Colin Ian King <colin.king@canonical.com>
> >>
> >> Reading and writing to mode[count - 1] implies the count should not
> >> be less than 1 so add a sanity check for this.
> >>
> >> Detected with CoverityScan, CID#1357345 ("Overflowed array index write")
> >>
> >> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> >
> > This is harmless, of course, but count can't be zero. This is a sysfs
> > file so we test for zero size writes in sysfs_kf_write() and return
> > early.
>
> Ah, thanks for pointing out that. I overlooked that detail.
>
The only reason I know this stuff is because it's annotated in Smatch.
So I do this:
diff --git a/drivers/scsi/fcoe/fcoe_sysfs.c b/drivers/scsi/fcoe/fcoe_sysfs.c
index 9cf3d56296ab..c491ad8fb0a8 100644
--- a/drivers/scsi/fcoe/fcoe_sysfs.c
+++ b/drivers/scsi/fcoe/fcoe_sysfs.c
@@ -281,6 +281,7 @@ static ssize_t show_ctlr_mode(struct device *dev,
"%s\n", name);
}
+#include "/home/dcarpenter/progs/smatch/devel/check_debug.h"
static ssize_t store_ctlr_mode(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
@@ -288,6 +289,7 @@ static ssize_t store_ctlr_mode(struct device *dev,
struct fcoe_ctlr_device *ctlr = dev_to_ctlr(dev);
char mode[FCOE_MAX_MODENAME_LEN + 1];
+ __smatch_implied(count);
if (count > FCOE_MAX_MODENAME_LEN)
return -EINVAL;
Then when I run kchecker drivers/scsi/fcoe/fcoe_sysfs.c, it tells me:
drivers/scsi/fcoe/fcoe_sysfs.c:292 store_ctlr_mode() implied: count = '1-1000000000,2147479552'
Which is sort of surprising... The 1000000000 value is a hack I made so
that it would never complain that "off + count" will wrap. But
apparently something has changed so it's also picking up the true limit
of count which is 2147479552.
Then I run the following commands to view the call tree:
smdb.py store_ctlr_mode
smdb.py dev_attr_store
smdb.py sysfs_kf_write
I have some vim macros so I can look these up really quickly.
regards,
dan carpenter
^ permalink raw reply related [flat|nested] 4+ messages in thread
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2017-03-22 14:01 [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option Colin King
2017-03-22 19:39 ` Dan Carpenter
2017-03-22 19:42 ` Colin Ian King
2017-03-23 11:45 ` Dan Carpenter
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