On Wed, Sep 21, 2022 at 11:28:35PM -0500, Gustavo A. R. Silva wrote: > One-element arrays are deprecated, and we are replacing them with flexible > array members instead. So, replace one-element array with flexible-array > member in struct MR_DRV_RAID_MAP and refactor the the rest of the code > accordingly. > > It seems that the addition of sizeof(struct report_log_lun) in all the > places that are modified by this patch is due to the fact that > the one-element array struct report_log_lun lun_entries[1]; always > contributes to the size of the containing structure struct > report_log_lun_list. > > Notice that at line 1267 while allocating memory for an instance of > struct report_log_lun_list, some _extra_ space seems to be allocated > for one element of type struct report_log_lun, which is the type of > the elements in array lun_entries: > > 1267 internal_logdev_list = kmalloc(logdev_data_length + > 1268 sizeof(struct report_log_lun), GFP_KERNEL); > > However, at line 1275 just logdev_data_length bytes are copied into > internal_logdev_list (remember that we allocated space for logdev_data_length + > sizeof(struct report_log_lun) bytes at line 1267), and then exactly > sizeof(struct report_log_lun) bytes are being zeroing out at line 1276. > > 1275 memcpy(internal_logdev_list, logdev_data, logdev_data_length); > 1276 memset((u8 *)internal_logdev_list + logdev_data_length, 0, > 1277 sizeof(struct report_log_lun)); > > All the above makes think that it's just fine if we transform array > lun_entries into a flexible-array member and just don't allocate > that extra sizeof(struct report_log_lun) bytes of space. With this > we can remove that memset() call and we also need to modify the code > that updates the total length (internal_logdev_list->header.list_length) > of array lun_entries at line 1278: > > 1278 put_unaligned_be32(logdev_list_length + > 1279 sizeof(struct report_log_lun), > 1280 &internal_logdev_list->header.list_length); > > This helps with the ongoing efforts to tighten the FORTIFY_SOURCE routines > on memcpy(). > > Link: https://github.com/KSPP/linux/issues/79 > Link: https://github.com/KSPP/linux/issues/204 > Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> > --- > And of course, it'd be great if maintainers can confirm what I described > in the changelog text. :) > > drivers/scsi/smartpqi/smartpqi.h | 2 +- > drivers/scsi/smartpqi/smartpqi_init.c | 10 +++------- > 2 files changed, 4 insertions(+), 8 deletions(-) > > diff --git a/drivers/scsi/smartpqi/smartpqi.h b/drivers/scsi/smartpqi/smartpqi.h > index e550b12e525a..d1756c9d1112 100644 > --- a/drivers/scsi/smartpqi/smartpqi.h > +++ b/drivers/scsi/smartpqi/smartpqi.h > @@ -954,7 +954,7 @@ struct report_log_lun { > > struct report_log_lun_list { > struct report_lun_header header; > - struct report_log_lun lun_entries[1]; > + struct report_log_lun lun_entries[]; > }; > > struct report_phys_lun_8byte_wwid { > diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c > index b971fbe3b3a1..544cd18a90d7 100644 > --- a/drivers/scsi/smartpqi/smartpqi_init.c > +++ b/drivers/scsi/smartpqi/smartpqi_init.c > @@ -1264,8 +1264,7 @@ static int pqi_get_device_lists(struct pqi_ctrl_info *ctrl_info, > logdev_data_length = sizeof(struct report_lun_header) + > logdev_list_length; > > - internal_logdev_list = kmalloc(logdev_data_length + > - sizeof(struct report_log_lun), GFP_KERNEL); > + internal_logdev_list = kmalloc(logdev_data_length, GFP_KERNEL); > if (!internal_logdev_list) { > kfree(*logdev_list); > *logdev_list = NULL; > @@ -1273,11 +1272,8 @@ static int pqi_get_device_lists(struct pqi_ctrl_info *ctrl_info, > } > > memcpy(internal_logdev_list, logdev_data, logdev_data_length); > - memset((u8 *)internal_logdev_list + logdev_data_length, 0, > - sizeof(struct report_log_lun)); > - put_unaligned_be32(logdev_list_length + > - sizeof(struct report_log_lun), > - &internal_logdev_list->header.list_length); > + put_unaligned_be32(logdev_list_length, > + &internal_logdev_list->header.list_length); This is a bit of a twisty maze to read through, but at the end, I agree with your assessment: it was needlessly added the extra member to the allocation. I don't see it used anywhere in later code -- it's always bounded by logdev_list_length. Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > > kfree(*logdev_list); > *logdev_list = internal_logdev_list; > -- > 2.34.1 > -- Kees Cook
