From: Letu Ren fantasquex@gmail.com
[ Upstream commit fbfe96869b782364caebae0445763969ddb6ea67 ]
In __qedf_probe(), if qedf->cdev is NULL which means qed_ops->common->probe() failed, then the program will goto label err1, and scsi_host_put() will free lport->host pointer. Because the memory qedf points to is allocated by libfc_host_alloc(), it will be freed by scsi_host_put(). However, the if statement below label err0 only checks whether qedf is NULL but doesn't check whether the memory has been freed. So a UAF bug can occur.
There are two ways to reach the statements below err0. The first one is described as before, "qedf" should be set to NULL. The second one is goto "err0" directly. In the latter scenario qedf hasn't been changed and it has the initial value NULL. As a result the if statement is not reachable in any situation.
The KASAN logs are as follows:
[ 2.312969] BUG: KASAN: use-after-free in __qedf_probe+0x5dcf/0x6bc0 [ 2.312969] [ 2.312969] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 [ 2.312969] Call Trace: [ 2.312969] dump_stack_lvl+0x59/0x7b [ 2.312969] print_address_description+0x7c/0x3b0 [ 2.312969] ? __qedf_probe+0x5dcf/0x6bc0 [ 2.312969] __kasan_report+0x160/0x1c0 [ 2.312969] ? __qedf_probe+0x5dcf/0x6bc0 [ 2.312969] kasan_report+0x4b/0x70 [ 2.312969] ? kobject_put+0x25d/0x290 [ 2.312969] kasan_check_range+0x2ca/0x310 [ 2.312969] __qedf_probe+0x5dcf/0x6bc0 [ 2.312969] ? selinux_kernfs_init_security+0xdc/0x5f0 [ 2.312969] ? trace_rpm_return_int_rcuidle+0x18/0x120 [ 2.312969] ? rpm_resume+0xa5c/0x16e0 [ 2.312969] ? qedf_get_generic_tlv_data+0x160/0x160 [ 2.312969] local_pci_probe+0x13c/0x1f0 [ 2.312969] pci_device_probe+0x37e/0x6c0
Link: https://lore.kernel.org/r/20211112120641.16073-1-fantasquex@gmail.com Reported-by: Zheyu Ma zheyuma97@gmail.com Acked-by: Saurav Kashyap skashyap@marvell.com Co-developed-by: Wende Tan twd2.me@gmail.com Signed-off-by: Wende Tan twd2.me@gmail.com Signed-off-by: Letu Ren fantasquex@gmail.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/qedf/qedf_main.c | 5 ----- 1 file changed, 5 deletions(-)
diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c index e64457f53da8..de5b6453827c 100644 --- a/drivers/scsi/qedf/qedf_main.c +++ b/drivers/scsi/qedf/qedf_main.c @@ -3671,11 +3671,6 @@ static int __qedf_probe(struct pci_dev *pdev, int mode) err1: scsi_host_put(lport->host); err0: - if (qedf) { - QEDF_INFO(&qedf->dbg_ctx, QEDF_LOG_DISC, "Probe done.\n"); - - clear_bit(QEDF_PROBING, &qedf->flags); - } return rc; }