| Message ID | 20231006201719.work.356-kees@kernel.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | wifi: p54: Annotate struct p54_cal_database with __counted_by | expand |
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
On 10/9/23 16:55, 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@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 I think you're right. More comments below... > 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. This should be changed to: - dst = kmalloc(sizeof(*dst) + payload_len, GFP_KERNEL); + dst = kmalloc(struct_size(dst, data, payload_len), GFP_KERNEL); > > I don't read Coccinelle, but, if this patch was auto-generated, I > wonder if the script has an error. With the struct_size() change, the Coccinelle script should be able to generate a correct patch for this. -- Gustavo
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@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. 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!
On Mon, Oct 09, 2023 at 10:55:32AM -0400, Jason Andryuk wrote: > 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. It seems that my Coccinelle script got confused by this: p54_convert_output_limits(): priv->output_limit = kmalloc(data[1] * sizeof(struct pda_channel_output_limit) + sizeof(*priv->output_limit), GFP_KERNEL); ... priv->output_limit->entry_size = sizeof(struct pda_channel_output_limit); priv->output_limit->len = priv->output_limit->entry_size * priv->output_limit->entries + priv->output_limit->offset; It thought "sizeof(struct pda_channel_output_limit)" was the element count, since it wasn't able to identify the array member here. Regardless, I've sent a v2 now. :)
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); }; #define EEPROM_READBACK_LEN 0x3fc
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(-)