On Mon, Oct 09, 2023 at 10:55:32AM -0400, Jason Andryuk wrote: > Hi, > > I randomly peeked at this patch. Unfortunately, I am not familiar > with the actual p54 code. > > On Fri, Oct 6, 2023 at 4:17 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > Prepare for the coming implementation by GCC and Clang of the __counted_by > > attribute. Flexible array members annotated with __counted_by can have > > their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for > > array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family > > functions). > > > > As found with Coccinelle[1], add __counted_by for struct p54_cal_database. > > > > Cc: Christian Lamparter <chunkeey@xxxxxxxxxxxxxx> > > Cc: Kalle Valo <kvalo@xxxxxxxxxx> > > Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx> > > Cc: linux-wireless@xxxxxxxxxxxxxxx > > Cc: linux-hardening@xxxxxxxxxxxxxxx > > Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1] > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > --- > > drivers/net/wireless/intersil/p54/p54.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/net/wireless/intersil/p54/p54.h b/drivers/net/wireless/intersil/p54/p54.h > > index 3356ea708d81..770e348d1f6c 100644 > > --- a/drivers/net/wireless/intersil/p54/p54.h > > +++ b/drivers/net/wireless/intersil/p54/p54.h > > @@ -126,7 +126,7 @@ struct p54_cal_database { > > size_t entry_size; > > size_t offset; > > size_t len; > > - u8 data[]; > > + u8 data[] __counted_by(entries); > > This looks incorrect - I think you want __counted_by(len)? The > presence of entry_size made me suspicious. > > > }; > > This is the function that creates struct p54_cal_database: > > static struct p54_cal_database *p54_convert_db(struct pda_custom_wrapper *src, > size_t total_len) > { > struct p54_cal_database *dst; > size_t payload_len, entries, entry_size, offset; > > payload_len = le16_to_cpu(src->len); > entries = le16_to_cpu(src->entries); > entry_size = le16_to_cpu(src->entry_size); > offset = le16_to_cpu(src->offset); > if (((entries * entry_size + offset) != payload_len) || > (payload_len + sizeof(*src) != total_len)) > return NULL; > > dst = kmalloc(sizeof(*dst) + payload_len, GFP_KERNEL); > if (!dst) > return NULL; > > dst->entries = entries; > dst->entry_size = entry_size; > dst->offset = offset; > dst->len = payload_len; > > memcpy(dst->data, src->data, payload_len); > return dst; > } > > You can see that kmalloc is performed with `sizeof(*dst) + > payload_len`, and payload_len is assigned to ->len. Agreed! > I don't read Coccinelle, but, if this patch was auto-generated, I > wonder if the script has an error. Yeah, I'm not sure which part went wrong. I will investigate. Thanks for catching this! -- Kees Cook
