From: Ye Bin Date: Wed, 13 Jan 2021 06:31:03 +0000 (+0800) Subject: scsi: scsi_dh_rdac: Avoid crash during rdac_bus_attach() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=110fde2fb2d3940953b5332a9c7ca296f9b9cd75;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git scsi: scsi_dh_rdac: Avoid crash during rdac_bus_attach() [ Upstream commit bc546c0c9abb3bb2fb46866b3d1e6ade9695a5f6 ] The following BUG_ON() was observed during RDAC scan: [595952.944297] kernel BUG at drivers/scsi/device_handler/scsi_dh_rdac.c:427! [595952.951143] Internal error: Oops - BUG: 0 [#1] SMP ...... [595953.251065] Call trace: [595953.259054] check_ownership+0xb0/0x118 [595953.269794] rdac_bus_attach+0x1f0/0x4b0 [595953.273787] scsi_dh_handler_attach+0x3c/0xe8 [595953.278211] scsi_dh_add_device+0xc4/0xe8 [595953.282291] scsi_sysfs_add_sdev+0x8c/0x2a8 [595953.286544] scsi_probe_and_add_lun+0x9fc/0xd00 [595953.291142] __scsi_scan_target+0x598/0x630 [595953.295395] scsi_scan_target+0x120/0x130 [595953.299481] fc_user_scan+0x1a0/0x1c0 [scsi_transport_fc] [595953.304944] store_scan+0xb0/0x108 [595953.308420] dev_attr_store+0x44/0x60 [595953.312160] sysfs_kf_write+0x58/0x80 [595953.315893] kernfs_fop_write+0xe8/0x1f0 [595953.319888] __vfs_write+0x60/0x190 [595953.323448] vfs_write+0xac/0x1c0 [595953.326836] ksys_write+0x74/0xf0 [595953.330221] __arm64_sys_write+0x24/0x30 Code is in check_ownership: list_for_each_entry_rcu(tmp, &h->ctlr->dh_list, node) { /* h->sdev should always be valid */ BUG_ON(!tmp->sdev); tmp->sdev->access_state = access_state; } rdac_bus_attach initialize_controller list_add_rcu(&h->node, &h->ctlr->dh_list); h->sdev = sdev; rdac_bus_detach list_del_rcu(&h->node); h->sdev = NULL; Fix the race between rdac_bus_attach() and rdac_bus_detach() where h->sdev is NULL when processing the RDAC attach. Link: https://lore.kernel.org/r/20210113063103.2698953-1-yebin10@huawei.com Reviewed-by: Bart Van Assche Signed-off-by: Ye Bin Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c index 06fbd0b0c68a..6ddb3e9f21ba 100644 --- a/drivers/scsi/device_handler/scsi_dh_rdac.c +++ b/drivers/scsi/device_handler/scsi_dh_rdac.c @@ -526,8 +526,8 @@ static int initialize_controller(struct scsi_device *sdev, if (!h->ctlr) err = SCSI_DH_RES_TEMP_UNAVAIL; else { - list_add_rcu(&h->node, &h->ctlr->dh_list); h->sdev = sdev; + list_add_rcu(&h->node, &h->ctlr->dh_list); } spin_unlock(&list_lock); } @@ -852,11 +852,11 @@ static void rdac_bus_detach( struct scsi_device *sdev ) spin_lock(&list_lock); if (h->ctlr) { list_del_rcu(&h->node); - h->sdev = NULL; kref_put(&h->ctlr->kref, release_controller); } spin_unlock(&list_lock); sdev->handler_data = NULL; + synchronize_rcu(); kfree(h); }