Re: Clang warnings in net/phonet

From: Nathan Chancellor
Date: Sat Jan 26 2019 - 03:10:42 EST


On Mon, Jan 07, 2019 at 07:54:20PM -0700, Nathan Chancellor wrote:
> Hi all,
>
> When building the kernel with Clang, this warning comes up in net/phonet.
>
> net/phonet/pep.c:224:16: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
> ph->data[0] = oph->data[1]; /* CTRL id */
> ^ ~
> include/net/phonet/pep.h:66:3: note: array 'data' declared here
> u8 data[1];
> ^
> net/phonet/pep.c:281:10: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
> switch (hdr->data[1]) {
> ^ ~
> include/net/phonet/pep.h:66:3: note: array 'data' declared here
> u8 data[1];
> ^
> net/phonet/pep.c:285:12: warning: array index 4 is past the end of the array (which contains 1 element) [-Warray-bounds]
> switch (hdr->data[4]) {
> ^ ~
> include/net/phonet/pep.h:66:3: note: array 'data' declared here
> u8 data[1];
> ^
> net/phonet/pep.c:295:8: warning: array index 4 is past the end of the array (which contains 1 element) [-Warray-bounds]
> if (hdr->data[4] == PEP_IND_READY)
> ^ ~
> include/net/phonet/pep.h:66:3: note: array 'data' declared here
> u8 data[1];
> ^
> net/phonet/pep.c:304:21: warning: array index 4 is past the end of the array (which contains 1 element) [-Warray-bounds]
> atomic_add(wake = hdr->data[4], &pn->tx_credits);
> ^ ~
> include/net/phonet/pep.h:66:3: note: array 'data' declared here
> u8 data[1];
> ^
> net/phonet/pep.c:509:9: warning: array index 4 is past the end of the array (which contains 1 element) [-Warray-bounds]
> n_sb = hdr->data[4];
> ^ ~
> include/net/phonet/pep.h:66:3: note: array 'data' declared here
> u8 data[1];
> ^
> net/phonet/pep.c:817:14: warning: array index 1 is past the end of the array (which contains 1 element) [-Warray-bounds]
> peer_type = hdr->other_pep_type << 8;
> ^ ~~~~~~~~~~~~~~
> include/net/phonet/pep.h:66:3: note: array 'data' declared here
> u8 data[1];
> ^
> net/phonet/pep.c:820:9: warning: array index 4 is past the end of the array (which contains 1 element) [-Warray-bounds]
> n_sb = hdr->data[4];
> ^ ~
> include/net/phonet/pep.h:66:3: note: array 'data' declared here
> u8 data[1];
> ^
> 8 warnings generated.
>
> I have taken a look at the effected code but I can't really figure out
> the proper fix for this warning (my knowledge of C just isn't there
> yet). Nick had suggested changing 'u8 data[1]' to 'u8 *data' in
> 'struct pnpipehdr', which seems logical but I can't say for sure. Any
> advice would be appreciated :)
>
> Thanks,
> Nathan

Gentle ping?