| Message ID | 20190729114936.6103-1-baijiaju1990@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] usb: storage: sddr55: Fix a possible null-pointer dereference in sddr55_transport() | expand |
Sorry, I forgot to send to Oliver, so send it again. On 2019/7/29 19:49, Jia-Ju Bai wrote: > In sddr55_transport(), there is an if statement on line 836 to check > whether info->lba_to_pba is NULL: > if (info->lba_to_pba == NULL || ...) > > When info->lba_to_pba is NULL, it is used on line 948: > pba = info->lba_to_pba[lba]; > > Thus, a possible null-pointer dereference may occur. > > To fix this bug, info->lba_to_pba is checked before being used. > > This bug is found by a static analysis tool STCheck written by us. > > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> > --- > v2: > * Avoid uninitialized access of pba. > Thank Oliver for helpful advice. > > --- > drivers/usb/storage/sddr55.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/usb/storage/sddr55.c b/drivers/usb/storage/sddr55.c > index b8527c55335b..d23aff16091e 100644 > --- a/drivers/usb/storage/sddr55.c > +++ b/drivers/usb/storage/sddr55.c > @@ -945,7 +945,7 @@ static int sddr55_transport(struct scsi_cmnd *srb, struct us_data *us) > return USB_STOR_TRANSPORT_FAILED; > } > > - pba = info->lba_to_pba[lba]; > + pba = info->lba_to_pba ? info->lba_to_pba[lba] : 0; > > if (srb->cmnd[0] == WRITE_10) { > usb_stor_dbg(us, "WRITE_10: write block %04X (LBA %04X) page %01X pages %d\n",
On Mon, 29 Jul 2019, Jia-Ju Bai wrote: > In sddr55_transport(), there is an if statement on line 836 to check > whether info->lba_to_pba is NULL: > if (info->lba_to_pba == NULL || ...) > > When info->lba_to_pba is NULL, it is used on line 948: > pba = info->lba_to_pba[lba]; > > Thus, a possible null-pointer dereference may occur. > > To fix this bug, info->lba_to_pba is checked before being used. > > This bug is found by a static analysis tool STCheck written by us. This is not the right way to fix the bug. The code already contains a test on line 938: if (lba >= info->max_log_blks) { If this test fails, the driver doesn't try to dereference info->lba_to_pba. The problem is that info->max_log_blks may be set even though info->lba_to_pba is NULL, because the READ_CAPACITY case in sddr55_transport() doesn't check the return code from sddr55_read_map(). _That_ is what needs to be fixed. Alan Stern > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> > --- > v2: > * Avoid uninitialized access of pba. > Thank Oliver for helpful advice. > > --- > drivers/usb/storage/sddr55.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/usb/storage/sddr55.c b/drivers/usb/storage/sddr55.c > index b8527c55335b..d23aff16091e 100644 > --- a/drivers/usb/storage/sddr55.c > +++ b/drivers/usb/storage/sddr55.c > @@ -945,7 +945,7 @@ static int sddr55_transport(struct scsi_cmnd *srb, struct us_data *us) > return USB_STOR_TRANSPORT_FAILED; > } > > - pba = info->lba_to_pba[lba]; > + pba = info->lba_to_pba ? info->lba_to_pba[lba] : 0; > > if (srb->cmnd[0] == WRITE_10) { > usb_stor_dbg(us, "WRITE_10: write block %04X (LBA %04X) page %01X pages %d\n", >
diff --git a/drivers/usb/storage/sddr55.c b/drivers/usb/storage/sddr55.c index b8527c55335b..d23aff16091e 100644 --- a/drivers/usb/storage/sddr55.c +++ b/drivers/usb/storage/sddr55.c @@ -945,7 +945,7 @@ static int sddr55_transport(struct scsi_cmnd *srb, struct us_data *us) return USB_STOR_TRANSPORT_FAILED; } - pba = info->lba_to_pba[lba]; + pba = info->lba_to_pba ? info->lba_to_pba[lba] : 0; if (srb->cmnd[0] == WRITE_10) { usb_stor_dbg(us, "WRITE_10: write block %04X (LBA %04X) page %01X pages %d\n",
In sddr55_transport(), there is an if statement on line 836 to check whether info->lba_to_pba is NULL: if (info->lba_to_pba == NULL || ...) When info->lba_to_pba is NULL, it is used on line 948: pba = info->lba_to_pba[lba]; Thus, a possible null-pointer dereference may occur. To fix this bug, info->lba_to_pba is checked before being used. This bug is found by a static analysis tool STCheck written by us. Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> --- v2: * Avoid uninitialized access of pba. Thank Oliver for helpful advice. --- drivers/usb/storage/sddr55.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)