Re: [PATCH v2] char: tpm: tpm-buf: Add sanity check fallback in read helpers

[Purva Yeshi]

On 11/04/25 12:50, Stefano Garzarella wrote:
> On Thu, Apr 10, 2025 at 04:04:42PM +0530, Purva Yeshi wrote:
> > Fix Smatch-detected issue:
> >
> > drivers/char/tpm/tpm-buf.c:208 tpm_buf_read_u8() error:
> > uninitialized symbol 'value'.
> > drivers/char/tpm/tpm-buf.c:225 tpm_buf_read_u16() error:
> > uninitialized symbol 'value'.
> > drivers/char/tpm/tpm-buf.c:242 tpm_buf_read_u32() error:
> > uninitialized symbol 'value'.
> >
> > Zero-initialize the return values in tpm_buf_read_u8(),
> > tpm_buf_read_u16(), and tpm_buf_read_u32() to guard against
> > uninitialized data in case of a boundary overflow.
> >
> > Add defensive initialization ensures the return values are
> > always defined, preventing undefined behavior if the unexpected
> > happens.
> >
> > Signed-off-by: Purva Yeshi <purvayeshi550@xxxxxxxxx>
> > ---
> > V1 - https://lore.kernel.org/all/20250409205536.210202-1- 
> > purvayeshi550@xxxxxxxxx/
> > V2 - Update commit message to clarify patch adds a sanity check
>
> LGTM!
>
> Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>

Thank you for the review.

> > drivers/char/tpm/tpm-buf.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
> > index e49a19fea3bd..dc882fc9fa9e 100644
> > --- a/drivers/char/tpm/tpm-buf.c
> > +++ b/drivers/char/tpm/tpm-buf.c
> > @@ -201,7 +201,7 @@ static void tpm_buf_read(struct tpm_buf *buf, 
> > off_t *offset, size_t count, void
> >  */
> > u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset)
> > {
> > -    u8 value;
> > +    u8 value = 0;
> >
> >     tpm_buf_read(buf, offset, sizeof(value), &value);
> >
> > @@ -218,7 +218,7 @@ EXPORT_SYMBOL_GPL(tpm_buf_read_u8);
> >  */
> > u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset)
> > {
> > -    u16 value;
> > +    u16 value = 0;
> >
> >     tpm_buf_read(buf, offset, sizeof(value), &value);
> >
> > @@ -235,7 +235,7 @@ EXPORT_SYMBOL_GPL(tpm_buf_read_u16);
> >  */
> > u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset)
> > {
> > -    u32 value;
> > +    u32 value = 0;
> >
> >     tpm_buf_read(buf, offset, sizeof(value), &value);
> >
> > --
> > 2.34.1

Best Regards,
Purva