On Tue, Aug 10, 2021 at 11:26:14AM -0500, Gustavo A. R. Silva wrote: > Hi Sakari, > > Please, see my comments below... > > On 8/10/21 10:18, Sakari Ailus wrote: > > Hi Gustavo, > > > > Apologies for the delay. > > > > On Mon, Aug 02, 2021 at 08:46:20AM -0500, Gustavo A. R. Silva wrote: > >> Hi Sakari, > >> > >> On 8/2/21 01:05, Sakari Ailus wrote: > >>> Hi Gustavo, > >>> > >>> I missed you already had sent v2... > >>> > >>> On Fri, Jul 30, 2021 at 07:08:13AM -0500, Gustavo A. R. Silva wrote: > >>>> There is a wrong comparison of the total size of the loaded firmware > >>>> css->fw->size with the size of a pointer to struct imgu_fw_header. > >>>> > >>>> Fix this by using the right operand 'struct imgu_fw_header' for > >>>> sizeof, instead of 'struct imgu_fw_header *' and turn binary_header > >>>> into a flexible-array member. Also, adjust the relational operator > >>>> to be '<=' instead of '<', as it seems that the intention of the > >>>> comparison is to determine if the loaded firmware contains any > >>>> 'struct imgu_fw_info' items in the binary_header[] array than merely > >>>> the file_header (struct imgu_fw_bi_file_h). > >>>> > >>>> The replacement of the one-element array with a flexible-array member > >>>> also help 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://github.com/KSPP/linux/issues/79 > >>>> Link: https://github.com/KSPP/linux/issues/109 > >>>> Fixes: 09d290f0ba21 ("media: staging/intel-ipu3: css: Add support for firmware management") > >>>> Cc: stable@xxxxxxxxxxxxxxx > >>>> Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> > >>>> --- > >>>> > >>>> It'd be just great if someone that knows this code better can confirm > >>>> these changes are correct. In particular the adjustment of the > >>>> relational operator. Thanks! > >>>> > >>>> Changes in v2: > >>>> - Use flexible array and adjust relational operator, accordingly. > >>> > >>> The operator was just correct. The check is just there to see the firmware > >>> is at least as large as the struct as which it is being accessed. > >> > >> I'm a bit confused, so based on your reply to v1 of this series, this patch > >> is now correct, right? > >> > >> The operator in v1 _was_ correct as long as the one-element array wasn't > >> transformed into a flexible array, right? > >> > >> Notice that generally speaking flexible-array members don't occupy space in the > >> containing structure: > >> > >> $ pahole -C imgu_fw_header drivers/staging/media/ipu3/ipu3-css-fw.o > >> struct imgu_fw_header { > >> struct imgu_fw_bi_file_h file_header; /* 0 72 */ > >> /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */ > >> struct imgu_fw_info binary_header[] __attribute__((__aligned__(8))); /* 72 0 */ > >> > >> /* size: 72, cachelines: 2, members: 2 */ > >> /* forced alignments: 1 */ > >> /* last cacheline: 8 bytes */ > >> } __attribute__((__aligned__(8))); > >> > >> $ pahole -C imgu_fw_header drivers/staging/media/ipu3/ipu3-css-fw.o > >> struct imgu_fw_header { > >> struct imgu_fw_bi_file_h file_header; /* 0 72 */ > >> /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */ > >> struct imgu_fw_info binary_header[1] __attribute__((__aligned__(8))); /* 72 1200 */ > >> > >> /* size: 1272, cachelines: 20, members: 2 */ > >> /* forced alignments: 1 */ > >> /* last cacheline: 56 bytes */ > >> } __attribute__((__aligned__(8))); > >> > >> So, now that the flexible array transformation is included in the same patch as the > >> bugfix, the operator is changed from '<' to '<=' > > > > '<' is correct since you only need as much data as the struct you're about > > to access is large, not a byte more than that. As Dan noted. > > > > I think you could add a check for binary_nr is at least one. > > If we need to check that binary_nr is at least one, then this would be the right > change: > > css->fwp = (struct imgu_fw_header *)css->fw->data; > - if (css->fw->size < sizeof(struct imgu_fw_header *) || > + if (css->fw->size < struct_size(css->fwp, binary_header, 1) || > css->fwp->file_header.h_size != sizeof(struct imgu_fw_bi_file_h)) > goto bad_fw; There's already a check the space required for the array of binary_nr is there. But not the number itself. -- Sakari Ailus
