[PATCH] security/integrity: fix pointer to ESL data and its size on pseries

[Jarkko Sakkinen]

On Wed Jun 7, 2023 at 3:28 PM EEST, Nayna wrote:
>
> On 6/6/23 16:51, Jarkko Sakkinen wrote:
> > On Tue Jun 6, 2023 at 8:26 PM EEST, Nayna Jain wrote:
> >> On PowerVM guest, variable data is prefixed with 8 bytes of timestamp.
> >> Extract ESL by stripping off the timestamp before passing to ESL parser.
> >>
> > Cc: stable at vger.kenrnel.org # v6.3
> >
> > ?
>
> Aah yes. Missed that.. Thanks..
>
>
> >
> >> Fixes: 4b3e71e9a34c ("integrity/powerpc: Support loading keys from PLPKS")
> >> Signed-off-by: Nayna Jain <nayna at linux.ibm.com>
> >> ---
> >>   .../integrity/platform_certs/load_powerpc.c   | 39 ++++++++++++-------
> >>   1 file changed, 26 insertions(+), 13 deletions(-)
> >>
> >> diff --git a/security/integrity/platform_certs/load_powerpc.c b/security/integrity/platform_certs/load_powerpc.c
> >> index b9de70b90826..57768cbf1fd3 100644
> >> --- a/security/integrity/platform_certs/load_powerpc.c
> >> +++ b/security/integrity/platform_certs/load_powerpc.c
> >> @@ -15,6 +15,9 @@
> >>   #include "keyring_handler.h"
> >>   #include "../integrity.h"
> >>   
> >> +#define extract_data(db, data, size, offset)	\
> >> +	do { db = data + offset; size = size - offset; } while (0)
> >> +
> >>   /*
> >>    * Get a certificate list blob from the named secure variable.
> >>    *
> >> @@ -55,8 +58,10 @@ static __init void *get_cert_list(u8 *key, unsigned long keylen, u64 *size)
> >>    */
> >>   static int __init load_powerpc_certs(void)
> >>   {
> >> +	void *data = NULL;
> >> +	u64 dsize = 0;
> >> +	u64 offset = 0;
> >>   	void *db = NULL, *dbx = NULL;
> > So... what do you need db still for?
> >
> > If you meant to rename 'db' to 'data', then you should not do it, since this is
> > a bug fix. It is zero gain, and a factor harder backport.
>
> In case of PowerVM guest, data points to timestamp + ESL.  And then with 
> offset of 8 bytes, db points to ESL.
>
> While db is used for parsing ESL, data is then later used to free 
> (timestamp + ESL) memory.
>
> Hope it answers the question.

OK, cool. Only thing I have to add that it would be more consistent if
data was declared in the same line as db and dbx, given that they are
declared in the same line.

BR, Jarkko