Commit c0014f94 authored by Daniel Wagner's avatar Daniel Wagner Committed by Martin K. Petersen
Browse files

scsi: qla2xxx: Warn if done() or free() are called on an already freed srb 

Emit a warning when ->done or ->free are called on an already freed
srb. There is a hidden use-after-free bug in the driver which corrupts
the srb memory pool which originates from the cleanup callbacks.

An extensive search didn't bring any lights on the real problem. The
initial fix was to set both pointers to NULL and try to catch invalid
accesses. But instead the memory corruption was gone and the driver
didn't crash. Since not all calling places check for NULL pointer, add
explicitly default handlers. With this we workaround the memory
corruption and add a debug help.

Link: https://lore.kernel.org/r/20200908081516.8561-2-dwagner@suse.de


Reviewed-by: default avatarMartin Wilck <mwilck@suse.com>
Reviewed-by: default avatarArun Easi <aeasi@marvell.com>
Signed-off-by: default avatarDaniel Wagner <dwagner@suse.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 988100a7

drivers/scsi/qla2xxx/qla_init.c

+10 −0
Original line number Diff line number Diff line
@@ -63,6 +63,16 @@ void qla2x00_sp_free(srb_t *sp) 
	qla2x00_rel_sp(sp);

}



void qla2xxx_rel_done_warning(srb_t *sp, int res)

{

	WARN_ONCE(1, "Calling done() of an already freed srb %p object\n", sp);

}



void qla2xxx_rel_free_warning(srb_t *sp)

{

	WARN_ONCE(1, "Calling free() of an already freed srb %p object\n", sp);

}



/* Asynchronous Login/Logout Routines -------------------------------------- */



unsigned long

drivers/scsi/qla2xxx/qla_inline.h

+5 −0
Original line number Diff line number Diff line
@@ -207,10 +207,15 @@ qla2xxx_get_qpair_sp(scsi_qla_host_t *vha, struct qla_qpair *qpair, 
	return sp;

}



void qla2xxx_rel_done_warning(srb_t *sp, int res);

void qla2xxx_rel_free_warning(srb_t *sp);



static inline void

qla2xxx_rel_qpair_sp(struct qla_qpair *qpair, srb_t *sp)

{

	sp->qpair = NULL;

	sp->done = qla2xxx_rel_done_warning;

	sp->free = qla2xxx_rel_free_warning;

	mempool_free(sp, qpair->srb_mempool);

	QLA_QPAIR_MARK_NOT_BUSY(qpair);

}