Re: [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
On Wed, Mar 22, 2017 at 07:42:08PM +, Colin Ian King wrote: > On 22/03/17 19:39, Dan Carpenter wrote: > > On Wed, Mar 22, 2017 at 02:01:37PM +, Colin King wrote: > >> From: Colin Ian King> >> > >> 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 > > > > 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 = '1-10,2147479552' Which is sort of surprising... The 10 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
Re: [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
On Wed, Mar 22, 2017 at 07:42:08PM +, Colin Ian King wrote: > On 22/03/17 19:39, Dan Carpenter wrote: > > On Wed, Mar 22, 2017 at 02:01:37PM +, Colin King wrote: > >> From: Colin Ian King > >> > >> 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 > > > > 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 = '1-10,2147479552' Which is sort of surprising... The 10 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
Re: [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
On 22/03/17 19:39, Dan Carpenter wrote: > On Wed, Mar 22, 2017 at 02:01:37PM +, Colin King wrote: >> From: Colin Ian King>> >> 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 > > 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 >
Re: [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
On 22/03/17 19:39, Dan Carpenter wrote: > On Wed, Mar 22, 2017 at 02:01:37PM +, Colin King wrote: >> From: Colin Ian King >> >> 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 > > 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 >
Re: [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
On Wed, Mar 22, 2017 at 02:01:37PM +, Colin King wrote: > From: Colin Ian King> > 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 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
Re: [PATCH] scsi: fcoe: sanity check string size for store_ctrl_mode option
On Wed, Mar 22, 2017 at 02:01:37PM +, Colin King wrote: > From: Colin Ian King > > 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 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