Issue :- BUG: unable to handle kernel NULL pointer dereference at 000000000000003c On installation of RHEL-8.3.0-20200820.n.0 distro below stack was generating on error. [ 14.042059] Call Trace: [ 14.042061] <IRQ> [ 14.042068] qedf_link_update+0x144/0x1f0 [qedf] [ 14.042117] qed_link_update+0x5c/0x80 [qed] [ 14.042135] qed_mcp_handle_link_change+0x2d2/0x410 [qed] [ 14.042155] ? qed_set_ptt+0x70/0x80 [qed] [ 14.042170] ? qed_set_ptt+0x70/0x80 [qed] [ 14.042186] ? qed_rd+0x13/0x40 [qed] [ 14.042205] qed_mcp_handle_events+0x437/0x690 [qed] [ 14.042221] ? qed_set_ptt+0x70/0x80 [qed] [ 14.042239] qed_int_sp_dpc+0x3a6/0x3e0 [qed] [ 14.042245] tasklet_action_common.isra.14+0x5a/0x100 [ 14.042250] __do_softirq+0xe4/0x2f8 [ 14.042253] irq_exit+0xf7/0x100 [ 14.042255] do_IRQ+0x7f/0xd0 [ 14.042257] common_interrupt+0xf/0xf [ 14.042259] </IRQ> Root cause :- API qedf_link_update() is getting called from QED. but by that time shost_data is not initialised. That is leading NULL pointer dereference when we try to derefference shost_data while updating supported_speeds. fc_host_supported_speeds(lport->host) = lport->link_supported_speeds; Expansion of fc_host_supported_speeds. #define fc_host_supported_speeds(x) \ (((struct fc_host_attrs *)(x)->shost_data)->supported_speeds) Fix :- Added NULL pointer check for shost_data. Signed-off-by: Javed Hasan <jhasan@xxxxxxxxxxx> diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c index 69f7784233f9..756231151882 100644 --- a/drivers/scsi/qedf/qedf_main.c +++ b/drivers/scsi/qedf/qedf_main.c @@ -536,7 +536,9 @@ static void qedf_update_link_speed(struct qedf_ctx *qedf, if (linkmode_intersects(link->supported_caps, sup_caps)) lport->link_supported_speeds |= FC_PORTSPEED_20GBIT; - fc_host_supported_speeds(lport->host) = lport->link_supported_speeds; + if (lport->host && lport->host->shost_data) + fc_host_supported_speeds(lport->host) = + lport->link_supported_speeds; } static void qedf_bw_update(void *dev) -- 2.18.2
