On Thu, Jun 23, 2022 at 08:19:49AM -0700, Kees Cook wrote: > On Thu, Jun 23, 2022 at 05:14:01AM +0200, Gustavo A. R. Silva wrote: > > On Thu, Jun 23, 2022 at 03:45:33AM +0200, Gustavo A. R. Silva wrote: > > > On Wed, Jun 22, 2022 at 03:26:38PM -0700, Kees Cook wrote: > > > > On Wed, Aug 04, 2021 at 11:20:04PM -0500, Gustavo A. R. Silva wrote: > > > > > Replace one-element array with a flexible-array member in struct > > > > > MR_DRV_RAID_MAP and use the flex_array_size() helper. > > > > > > > > > > This helps with the ongoing efforts to globally enable -Warray-bounds > > > > > and get us closer to being able to tighten the FORTIFY_SOURCE routines > > > > > on memcpy(). > > > > > > > > > > Link: https://en.wikipedia.org/wiki/Flexible_array_member > > > > > Link: https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays > > > > > Link: https://github.com/KSPP/linux/issues/79 > > > > > Link: https://github.com/KSPP/linux/issues/109 > > > > > Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> > > > > > > > > I'd really like to see this fixed. :) I'm running into this 1-element > > > > array problem now with UBSAN_BOUNDS: > > > > > > Wow; another forgoten patch from the times we didn't have Patchwork. :) > > > > > > > > > > > [ 10.011173] UBSAN: array-index-out-of-bounds in /build/linux-WLUive/linux-5.15.0/drivers/scsi/megaraid/megaraid_sas_fp.c:103:32 > > > > [ 10.087824] index 1 is out of range for type 'MR_LD_SPAN_MAP [1]' > > > > > > > > and I'm not the only one: > > > > > > > > https://bugzilla.kernel.org/show_bug.cgi?id=215943 > > > > > > It's actually great that other people are running into these issues now. > > > That could only means that we should fixed ASAP. :) > > > > > > We also have this other series that hasn't been applied yet: > > > > > > https://lore.kernel.org/linux-hardening/cover.1645513670.git.gustavoars@xxxxxxxxxx/ > > > > > > > > > > > > --- > > > > > Changes in v2: > > > > > - None. > > > > > > > > > > drivers/scsi/megaraid/megaraid_sas_fp.c | 6 +++--- > > > > > drivers/scsi/megaraid/megaraid_sas_fusion.h | 2 +- > > > > > 2 files changed, 4 insertions(+), 4 deletions(-) > > > > > > > > > > diff --git a/drivers/scsi/megaraid/megaraid_sas_fp.c b/drivers/scsi/megaraid/megaraid_sas_fp.c > > > > > index da1cad1ee123..9cb36ef96c2c 100644 > > > > > --- a/drivers/scsi/megaraid/megaraid_sas_fp.c > > > > > +++ b/drivers/scsi/megaraid/megaraid_sas_fp.c > > > > > @@ -229,8 +229,8 @@ static int MR_PopulateDrvRaidMap(struct megasas_instance *instance, u64 map_id) > > > > > le32_to_cpu(desc_table->raid_map_desc_offset)); > > > > > memcpy(pDrvRaidMap->ldSpanMap, > > > > > fw_map_dyn->ld_span_map, > > > > > - sizeof(struct MR_LD_SPAN_MAP) * > > > > > - le32_to_cpu(desc_table->raid_map_desc_elements)); > > > > > + flex_array_size(pDrvRaidMap, ldSpanMap, > > > > > + le32_to_cpu(desc_table->raid_map_desc_elements))); > > > > > break; > > > > > default: > > > > > dev_dbg(&instance->pdev->dev, "wrong number of desctableElements %d\n", > > > > > @@ -254,7 +254,7 @@ static int MR_PopulateDrvRaidMap(struct megasas_instance *instance, u64 map_id) > > > > > pDrvRaidMap->ldTgtIdToLd[i] = > > > > > (u16)fw_map_ext->ldTgtIdToLd[i]; > > > > > memcpy(pDrvRaidMap->ldSpanMap, fw_map_ext->ldSpanMap, > > > > > - sizeof(struct MR_LD_SPAN_MAP) * ld_count); > > > > > + flex_array_size(pDrvRaidMap, ldSpanMap, ld_count)); > > > > > memcpy(pDrvRaidMap->arMapInfo, fw_map_ext->arMapInfo, > > > > > sizeof(struct MR_ARRAY_INFO) * MAX_API_ARRAYS_EXT); > > > > > memcpy(pDrvRaidMap->devHndlInfo, fw_map_ext->devHndlInfo, > > > > > diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.h b/drivers/scsi/megaraid/megaraid_sas_fusion.h > > > > > index 9adb8b30f422..5fe2f7a6eebe 100644 > > > > > --- a/drivers/scsi/megaraid/megaraid_sas_fusion.h > > > > > +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.h > > > > > @@ -1182,7 +1182,7 @@ struct MR_DRV_RAID_MAP { > > > > > devHndlInfo[MAX_RAIDMAP_PHYSICAL_DEVICES_DYN]; > > > > > u16 ldTgtIdToLd[MAX_LOGICAL_DRIVES_DYN]; > > > > > struct MR_ARRAY_INFO arMapInfo[MAX_API_ARRAYS_DYN]; > > > > > - struct MR_LD_SPAN_MAP ldSpanMap[1]; > > > > > + struct MR_LD_SPAN_MAP ldSpanMap[]; > > > > > > > > > > }; > > > > > > > > > > > > > I think this patch is incomplete, and the wrapping struct needs to be > > > > adjusted too: > > > > > > > > @@ -1193,7 +1193,7 @@ struct MR_DRV_RAID_MAP { > > > > struct MR_DRV_RAID_MAP_ALL { > > > > > > > > struct MR_DRV_RAID_MAP raidMap; > > > > - struct MR_LD_SPAN_MAP ldSpanMap[MAX_LOGICAL_DRIVES_DYN - 1]; > > > > + struct MR_LD_SPAN_MAP ldSpanMap[MAX_LOGICAL_DRIVES_DYN]; > > > > } __packed; > > > > BTW, I'd really like to get some input from the maintainers of this > > code. :) > > Agreed, though if we get 0 output from a diffoscope of the object files, > I think it's safe to carry such patches in our trees. This is how I've > been testing: Which object files are you comparing here? because I don't see the zero change when comparing the before and after of megaraid_sas_fp.o with the change you propose. > > $ make allmodconfig > $ ./scripts/config -d GCOV_KERNEL -d KCOV -d GCC_PLUGINS -d IKHEADERS -d KASAN -d UBSAN > $ make olddefconfig > $ make the/path/to/code.o > $ cp the/path/to/code.o the/path/to/code.before > $ *apply patch* > $ make the/path/to/code.o > $ cp the/path/to/code.o the/path/to/code.after > $ diffoscope the/path/to/code.before the/path/to/code.after Yep; that's how we do it. However, I think the zero change is the exception, not the norm in these sorts of changes. The machine code could easily change after refactoring the code a bit as a consequence of the flex-array transformation. It's not like we are merely removing the 1 from the array declaration. We are also making use of helpers like struct_size(), flex_array_size() and in some cases we are making the code to stop allocating some too-many extra bytes (which usually account for the size of one item of the trailing array) that are never actually used. I think that could easily impact how the compiler ultimately arrange the code. -- Gustavo
