* [PATCH][next] tpm: xen-tpmfront: Use struct_size() helper
@ 2022-01-19 23:38 Gustavo A. R. Silva
2022-01-26 14:38 ` Jarkko Sakkinen
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2022-01-19 23:38 UTC (permalink / raw)
To: Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe
Cc: linux-integrity, linux-kernel, Gustavo A. R. Silva, linux-hardening
Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows that,
in the worse scenario, could lead to heap overflows.
Also, address the following sparse warning:
drivers/char/tpm/xen-tpmfront.c:131:16: warning: using sizeof on a flexible structure
Link: https://github.com/KSPP/linux/issues/160
Link: https://github.com/KSPP/linux/issues/174
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/char/tpm/xen-tpmfront.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
index da5b30771418..f53e0cf1ec7e 100644
--- a/drivers/char/tpm/xen-tpmfront.c
+++ b/drivers/char/tpm/xen-tpmfront.c
@@ -126,16 +126,16 @@ static void vtpm_cancel(struct tpm_chip *chip)
notify_remote_via_evtchn(priv->evtchn);
}
-static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
+static size_t shr_data_offset(struct vtpm_shared_page *shr)
{
- return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages;
+ return struct_size(shr, extra_pages, shr->nr_extra_pages);
}
static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
{
struct tpm_private *priv = dev_get_drvdata(&chip->dev);
struct vtpm_shared_page *shr = priv->shr;
- unsigned int offset = shr_data_offset(shr);
+ size_t offset = shr_data_offset(shr);
u32 ordinal;
unsigned long duration;
@@ -177,7 +177,7 @@ static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
struct tpm_private *priv = dev_get_drvdata(&chip->dev);
struct vtpm_shared_page *shr = priv->shr;
- unsigned int offset = shr_data_offset(shr);
+ size_t offset = shr_data_offset(shr);
size_t length = shr->length;
if (shr->state == VTPM_STATE_IDLE)
--
2.27.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH][next] tpm: xen-tpmfront: Use struct_size() helper
2022-01-19 23:38 [PATCH][next] tpm: xen-tpmfront: Use struct_size() helper Gustavo A. R. Silva
@ 2022-01-26 14:38 ` Jarkko Sakkinen
0 siblings, 0 replies; 2+ messages in thread
From: Jarkko Sakkinen @ 2022-01-26 14:38 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Peter Huewe, Jason Gunthorpe, linux-integrity, linux-kernel,
linux-hardening
On Wed, Jan 19, 2022 at 05:38:03PM -0600, Gustavo A. R. Silva wrote:
> Make use of the struct_size() helper instead of an open-coded version,
> in order to avoid any potential type mistakes or integer overflows that,
> in the worse scenario, could lead to heap overflows.
>
> Also, address the following sparse warning:
> drivers/char/tpm/xen-tpmfront.c:131:16: warning: using sizeof on a flexible structure
>
> Link: https://github.com/KSPP/linux/issues/160
> Link: https://github.com/KSPP/linux/issues/174
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> ---
> drivers/char/tpm/xen-tpmfront.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
> index da5b30771418..f53e0cf1ec7e 100644
> --- a/drivers/char/tpm/xen-tpmfront.c
> +++ b/drivers/char/tpm/xen-tpmfront.c
> @@ -126,16 +126,16 @@ static void vtpm_cancel(struct tpm_chip *chip)
> notify_remote_via_evtchn(priv->evtchn);
> }
>
> -static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
> +static size_t shr_data_offset(struct vtpm_shared_page *shr)
> {
> - return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages;
> + return struct_size(shr, extra_pages, shr->nr_extra_pages);
> }
>
> static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
> {
> struct tpm_private *priv = dev_get_drvdata(&chip->dev);
> struct vtpm_shared_page *shr = priv->shr;
> - unsigned int offset = shr_data_offset(shr);
> + size_t offset = shr_data_offset(shr);
>
> u32 ordinal;
> unsigned long duration;
> @@ -177,7 +177,7 @@ static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> {
> struct tpm_private *priv = dev_get_drvdata(&chip->dev);
> struct vtpm_shared_page *shr = priv->shr;
> - unsigned int offset = shr_data_offset(shr);
> + size_t offset = shr_data_offset(shr);
> size_t length = shr->length;
>
> if (shr->state == VTPM_STATE_IDLE)
> --
> 2.27.0
>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
BR, Jarkko
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