On Tue, Sep 12, 2023 at 11:43:05PM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> In this case, strncpy is being used specifically for its NUL-padding
> behavior (and has been commented as such). We can use a more robust and
> less ambiguous interface in `strscpy_pad` which makes the code more
> readable and even eliminates the need for that comment.
>
> Let's also use `strnlen` instead of `strlen()` with an upper-bounds
> check as this is intrinsically a part of `strnlen`.
>
> Also included in this patch is a simple 1:1 change of `strncpy` to
> `strscpy` for ipmi_ssif.c. If NUL-padding is wanted here as well then we
> should opt again for `strscpy_pad`.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> drivers/char/ipmi/ipmi_msghandler.c | 11 +++--------
> drivers/char/ipmi/ipmi_ssif.c | 2 +-
> 2 files changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> index 186f1fee7534..04f7622cb703 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -5377,20 +5377,15 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
>
> j = 0;
> while (*p) {
> - int size = strlen(p);
> + int size = strnlen(p, 11);
>
> - if (size > 11)
> - size = 11;
> data[0] = 0;
> data[1] = 0;
> data[2] = 0xf0; /* OEM event without timestamp. */
> data[3] = intf->addrinfo[0].address;
> data[4] = j++; /* sequence # */
> - /*
> - * Always give 11 bytes, so strncpy will fill
> - * it with zeroes for me.
> - */
> - strncpy(data+5, p, 11);
> +
> + strscpy_pad(data+5, p, 11);
This is incorrect, the destination should *not* be nil terminated if the
destination is full. strncpy does exactly what is needed here.
A comment should be added here, this is not the first time this has been
brought up.
> p += size;
>
> ipmi_panic_request_and_wait(intf, &addr, &msg);
> diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> index 3b921c78ba08..edcb83765dce 100644
> --- a/drivers/char/ipmi/ipmi_ssif.c
> +++ b/drivers/char/ipmi/ipmi_ssif.c
> @@ -1940,7 +1940,7 @@ static int new_ssif_client(int addr, char *adapter_name,
> }
> }
>
> - strncpy(addr_info->binfo.type, DEVICE_NAME,
> + strscpy(addr_info->binfo.type, DEVICE_NAME,
> sizeof(addr_info->binfo.type));
This one is good.
-corey
> addr_info->binfo.addr = addr;
> addr_info->binfo.platform_data = addr_info;
>
> ---
> base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
> change-id: 20230912-strncpy-drivers-char-ipmi-ipmi-dda47b3773fd
>
> Best regards,
> --
> Justin Stitt <[email protected]>
>
On Tue, Sep 12, 2023 at 5:19 PM Corey Minyard <[email protected]> wrote:
>
> On Tue, Sep 12, 2023 at 11:43:05PM +0000, Justin Stitt wrote:
> > `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> >
> > In this case, strncpy is being used specifically for its NUL-padding
> > behavior (and has been commented as such). We can use a more robust and
> > less ambiguous interface in `strscpy_pad` which makes the code more
> > readable and even eliminates the need for that comment.
> >
> > Let's also use `strnlen` instead of `strlen()` with an upper-bounds
> > check as this is intrinsically a part of `strnlen`.
> >
> > Also included in this patch is a simple 1:1 change of `strncpy` to
> > `strscpy` for ipmi_ssif.c. If NUL-padding is wanted here as well then we
> > should opt again for `strscpy_pad`.
> >
> > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> > Link: https://github.com/KSPP/linux/issues/90
> > Cc: [email protected]
> > Cc: Kees Cook <[email protected]>
> > Signed-off-by: Justin Stitt <[email protected]>
> > ---
> > drivers/char/ipmi/ipmi_msghandler.c | 11 +++--------
> > drivers/char/ipmi/ipmi_ssif.c | 2 +-
> > 2 files changed, 4 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> > index 186f1fee7534..04f7622cb703 100644
> > --- a/drivers/char/ipmi/ipmi_msghandler.c
> > +++ b/drivers/char/ipmi/ipmi_msghandler.c
> > @@ -5377,20 +5377,15 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
> >
> > j = 0;
> > while (*p) {
> > - int size = strlen(p);
> > + int size = strnlen(p, 11);
> >
> > - if (size > 11)
> > - size = 11;
> > data[0] = 0;
> > data[1] = 0;
> > data[2] = 0xf0; /* OEM event without timestamp. */
> > data[3] = intf->addrinfo[0].address;
> > data[4] = j++; /* sequence # */
> > - /*
> > - * Always give 11 bytes, so strncpy will fill
> > - * it with zeroes for me.
> > - */
> > - strncpy(data+5, p, 11);
> > +
> > + strscpy_pad(data+5, p, 11);
>
> This is incorrect, the destination should *not* be nil terminated if the
> destination is full. strncpy does exactly what is needed here.
Could we use `memcpy_and_pad()` as this matches the behavior of
strncpy in this case? I understand strncpy works here but I'm really
keen on snuffing out all its uses -- treewide.
>
> A comment should be added here, this is not the first time this has been
> brought up.
>
> > p += size;
> >
> > ipmi_panic_request_and_wait(intf, &addr, &msg);
> > diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> > index 3b921c78ba08..edcb83765dce 100644
> > --- a/drivers/char/ipmi/ipmi_ssif.c
> > +++ b/drivers/char/ipmi/ipmi_ssif.c
> > @@ -1940,7 +1940,7 @@ static int new_ssif_client(int addr, char *adapter_name,
> > }
> > }
> >
> > - strncpy(addr_info->binfo.type, DEVICE_NAME,
> > + strscpy(addr_info->binfo.type, DEVICE_NAME,
> > sizeof(addr_info->binfo.type));
>
> This one is good.
>
> -corey
>
> > addr_info->binfo.addr = addr;
> > addr_info->binfo.platform_data = addr_info;
> >
> > ---
> > base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
> > change-id: 20230912-strncpy-drivers-char-ipmi-ipmi-dda47b3773fd
> >
> > Best regards,
> > --
> > Justin Stitt <[email protected]>
> >
On Tue, Sep 12, 2023 at 5:55 PM Justin Stitt <[email protected]> wrote:
>
> On Tue, Sep 12, 2023 at 5:19 PM Corey Minyard <[email protected]> wrote:
> >
> > On Tue, Sep 12, 2023 at 11:43:05PM +0000, Justin Stitt wrote:
> > > `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> > >
> > > In this case, strncpy is being used specifically for its NUL-padding
> > > behavior (and has been commented as such). We can use a more robust and
> > > less ambiguous interface in `strscpy_pad` which makes the code more
> > > readable and even eliminates the need for that comment.
> > >
> > > Let's also use `strnlen` instead of `strlen()` with an upper-bounds
> > > check as this is intrinsically a part of `strnlen`.
> > >
> > > Also included in this patch is a simple 1:1 change of `strncpy` to
> > > `strscpy` for ipmi_ssif.c. If NUL-padding is wanted here as well then we
> > > should opt again for `strscpy_pad`.
> > >
> > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> > > Link: https://github.com/KSPP/linux/issues/90
> > > Cc: [email protected]
> > > Cc: Kees Cook <[email protected]>
> > > Signed-off-by: Justin Stitt <[email protected]>
> > > ---
> > > drivers/char/ipmi/ipmi_msghandler.c | 11 +++--------
> > > drivers/char/ipmi/ipmi_ssif.c | 2 +-
> > > 2 files changed, 4 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> > > index 186f1fee7534..04f7622cb703 100644
> > > --- a/drivers/char/ipmi/ipmi_msghandler.c
> > > +++ b/drivers/char/ipmi/ipmi_msghandler.c
> > > @@ -5377,20 +5377,15 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
> > >
> > > j = 0;
> > > while (*p) {
> > > - int size = strlen(p);
> > > + int size = strnlen(p, 11);
> > >
> > > - if (size > 11)
> > > - size = 11;
> > > data[0] = 0;
> > > data[1] = 0;
> > > data[2] = 0xf0; /* OEM event without timestamp. */
> > > data[3] = intf->addrinfo[0].address;
> > > data[4] = j++; /* sequence # */
> > > - /*
> > > - * Always give 11 bytes, so strncpy will fill
> > > - * it with zeroes for me.
> > > - */
> > > - strncpy(data+5, p, 11);
> > > +
> > > + strscpy_pad(data+5, p, 11);
> >
> > This is incorrect, the destination should *not* be nil terminated if the
> > destination is full. strncpy does exactly what is needed here.
>
> Could we use `memcpy_and_pad()` as this matches the behavior of
> strncpy in this case? I understand strncpy works here but I'm really
> keen on snuffing out all its uses -- treewide.
^ I mean something like the following:
| memcpy_and_pad(data+5, 11, p, size, '\0');
as this is explicit in its behavior.
>
> >
> > A comment should be added here, this is not the first time this has been
> > brought up.
> >
> > > p += size;
> > >
> > > ipmi_panic_request_and_wait(intf, &addr, &msg);
> > > diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> > > index 3b921c78ba08..edcb83765dce 100644
> > > --- a/drivers/char/ipmi/ipmi_ssif.c
> > > +++ b/drivers/char/ipmi/ipmi_ssif.c
> > > @@ -1940,7 +1940,7 @@ static int new_ssif_client(int addr, char *adapter_name,
> > > }
> > > }
> > >
> > > - strncpy(addr_info->binfo.type, DEVICE_NAME,
> > > + strscpy(addr_info->binfo.type, DEVICE_NAME,
> > > sizeof(addr_info->binfo.type));
> >
> > This one is good.
> >
> > -corey
> >
> > > addr_info->binfo.addr = addr;
> > > addr_info->binfo.platform_data = addr_info;
> > >
> > > ---
> > > base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
> > > change-id: 20230912-strncpy-drivers-char-ipmi-ipmi-dda47b3773fd
> > >
> > > Best regards,
> > > --
> > > Justin Stitt <[email protected]>
> > >
On Tue, Sep 12, 2023 at 05:55:02PM -0700, Justin Stitt wrote:
> On Tue, Sep 12, 2023 at 5:19 PM Corey Minyard <[email protected]> wrote:
> >
> > On Tue, Sep 12, 2023 at 11:43:05PM +0000, Justin Stitt wrote:
> > > `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> > >
> > > In this case, strncpy is being used specifically for its NUL-padding
> > > behavior (and has been commented as such). We can use a more robust and
> > > less ambiguous interface in `strscpy_pad` which makes the code more
> > > readable and even eliminates the need for that comment.
> > >
> > > Let's also use `strnlen` instead of `strlen()` with an upper-bounds
> > > check as this is intrinsically a part of `strnlen`.
> > >
> > > Also included in this patch is a simple 1:1 change of `strncpy` to
> > > `strscpy` for ipmi_ssif.c. If NUL-padding is wanted here as well then we
> > > should opt again for `strscpy_pad`.
> > >
> > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> > > Link: https://github.com/KSPP/linux/issues/90
> > > Cc: [email protected]
> > > Cc: Kees Cook <[email protected]>
> > > Signed-off-by: Justin Stitt <[email protected]>
> > > ---
> > > drivers/char/ipmi/ipmi_msghandler.c | 11 +++--------
> > > drivers/char/ipmi/ipmi_ssif.c | 2 +-
> > > 2 files changed, 4 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> > > index 186f1fee7534..04f7622cb703 100644
> > > --- a/drivers/char/ipmi/ipmi_msghandler.c
> > > +++ b/drivers/char/ipmi/ipmi_msghandler.c
> > > @@ -5377,20 +5377,15 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
> > >
> > > j = 0;
> > > while (*p) {
> > > - int size = strlen(p);
> > > + int size = strnlen(p, 11);
> > >
> > > - if (size > 11)
> > > - size = 11;
> > > data[0] = 0;
> > > data[1] = 0;
> > > data[2] = 0xf0; /* OEM event without timestamp. */
> > > data[3] = intf->addrinfo[0].address;
> > > data[4] = j++; /* sequence # */
> > > - /*
> > > - * Always give 11 bytes, so strncpy will fill
> > > - * it with zeroes for me.
> > > - */
> > > - strncpy(data+5, p, 11);
> > > +
> > > + strscpy_pad(data+5, p, 11);
> >
> > This is incorrect, the destination should *not* be nil terminated if the
> > destination is full. strncpy does exactly what is needed here.
>
> Could we use `memcpy_and_pad()` as this matches the behavior of
> strncpy in this case? I understand strncpy works here but I'm really
> keen on snuffing out all its uses -- treewide.
Sure, I think "memcpy_and_pad(data + 5, 11, p, size, 0);" should work.
And that's self-documenting.
-corey
>
> >
> > A comment should be added here, this is not the first time this has been
> > brought up.
> >
> > > p += size;
> > >
> > > ipmi_panic_request_and_wait(intf, &addr, &msg);
> > > diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> > > index 3b921c78ba08..edcb83765dce 100644
> > > --- a/drivers/char/ipmi/ipmi_ssif.c
> > > +++ b/drivers/char/ipmi/ipmi_ssif.c
> > > @@ -1940,7 +1940,7 @@ static int new_ssif_client(int addr, char *adapter_name,
> > > }
> > > }
> > >
> > > - strncpy(addr_info->binfo.type, DEVICE_NAME,
> > > + strscpy(addr_info->binfo.type, DEVICE_NAME,
> > > sizeof(addr_info->binfo.type));
> >
> > This one is good.
> >
> > -corey
> >
> > > addr_info->binfo.addr = addr;
> > > addr_info->binfo.platform_data = addr_info;
> > >
> > > ---
> > > base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
> > > change-id: 20230912-strncpy-drivers-char-ipmi-ipmi-dda47b3773fd
> > >
> > > Best regards,
> > > --
> > > Justin Stitt <[email protected]>
> > >