On Fri, Oct 28, 2022 at 05:43:03PM +0300, Dan Carpenter wrote: > On Fri, Oct 28, 2022 at 07:41:54PM +0530, Deepak R Varma wrote: > > On Fri, Oct 28, 2022 at 05:03:25PM +0300, Pavel Skripkin wrote: > > > Hi Deepak R, > > > > > > Deepak R Varma <drv@xxxxxxxxx> says: > > > > Flexible-array member should be used instead of one or zero member to > > > > meet the need for having a dynamically sized trailing elements in a > > > > structure. Refer to links [1] and [2] for detailed guidance on this > > > > suggestion. > > > > > > > > [1] https://en.wikipedia.org/wiki/Flexible_array_member > > > > [2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays > > > > > > > > Issue identified using coccicheck. > > > > > > > > Signed-off-by: Deepak R Varma <drv@xxxxxxxxx> > > > > --- > > > > drivers/staging/r8188eu/include/odm.h | 2 +- > > > > drivers/staging/r8188eu/include/wlan_bssdef.h | 6 +++--- > > > > 2 files changed, 4 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/drivers/staging/r8188eu/include/odm.h b/drivers/staging/r8188eu/include/odm.h > > > > index 89b01dd614ba..e2a9de5b9323 100644 > > > > --- a/drivers/staging/r8188eu/include/odm.h > > > > +++ b/drivers/staging/r8188eu/include/odm.h > > > > @@ -166,7 +166,7 @@ struct odm_ra_info { > > > > > > > > struct ijk_matrix_regs_set { > > > > bool bIQKDone; > > > > - s32 Value[1][IQK_Matrix_REG_NUM]; > > > > + s32 Value[][IQK_Matrix_REG_NUM]; > > > > }; > > > > > > > > > > you are changing the actual size of the struct. Wondering if you have tested > > > this patch somehow > > > > Hello Pavel, > > Thank you for reviewing the patch. I build the module post making the changes an > > ensured that the build is successful. However, I am not sure how to check the > > changes I am proposing. Could you please direct me to some information on how to > > test patches? Is there some documentation generic/driver-specific that I can > > refer to? > > You just have to look at every place where it is used and especially > look at where it is allocated. It is only used in one place: > > struct ijk_matrix_regs_set IQKMatrixRegSetting; > > But that is in the middle of a struct and generally it doesn't make > sense to have a flex array in the middle of a struct. So investigating > further, we see that it really is a one element array: > > Do a grep: > > pDM_Odm->RFCalibrateInfo.IQKMatrixRegSetting[ChannelMappedIndex].Value[0][1]); > > The first element is always zero. So this patch introduces memory > corruption. > > The code is messy and should be cleaned up, of course. Hello Pavel and Dan, I looked at the surround code and places where the proposed patch will have an impact. As you rightly pointed out this array can't be treated as a flexible array since it fits right in the middle of another struct. I am wondering if ijk_matrix_regs_set (or IQKMatrixRegSetting) is a one element array, why is it declared as a two dimensional array? Can this be a simple one dimensional array instead? Is this the cleanup you are referring to when you say "code is messy and should be cleaned up"? Thank you, ./drv > > regards, > dan carpenter >
