Messages in this thread | | | From | Jason Andryuk <> | Date | Mon, 9 Oct 2023 10:55:32 -0400 | Subject | Re: [PATCH] wifi: p54: Annotate struct p54_cal_database with __counted_by |
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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@chromium.org> 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@googlemail.com> > Cc: Kalle Valo <kvalo@kernel.org> > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > Cc: linux-wireless@vger.kernel.org > Cc: linux-hardening@vger.kernel.org > Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1] > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > 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.
I don't read Coccinelle, but, if this patch was auto-generated, I wonder if the script has an error.
Regards, Jason
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