Re: [PATCH -next V2 1/2] sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl

From: Sergei Shtylyov
Date: Sat Nov 20 2021 - 07:01:49 EST


On 20.11.2021 6:34, Baokun Li wrote:

When the `rmmod sata_fsl.ko` command is executed in the PPC64 GNU/Linux,
a bug is reported:
BUG: Unable to handle kernel data access on read at 0x80000800805b502c
Oops: Kernel access of bad area, sig: 11 [#1]
NIP [c0000000000388a4] .ioread32+0x4/0x20
LR [80000000000c6034] .sata_fsl_port_stop+0x44/0xe0 [sata_fsl]
Call Trace:
.free_irq+0x1c/0x4e0 (unreliable)
.ata_host_stop+0x74/0xd0 [libata]
.fsl_sata_driver_exit+0x18/0xa20 [sata_fsl]

The triggering of the BUG is shown in the following stack:

drv->remove(dev) --> platform_drv_remove/platform_remove
drv->remove(dev) --> sata_fsl_remove
iounmap(host_priv->hcr_base); <---- unmap
kfree(host_priv); <---- free
dr->node.release(dev, dr->data) --> ata_host_stop
ap->ops->port_stop(ap) --> sata_fsl_port_stop
ioread32(hcr_base + HCONTROL) <---- UAF

The iounmap(host_priv->hcr_base) and kfree(host_priv) commands should


not be executed in drv->remove. These commands should be executed in
host_stop after port_stop. Therefore, we move these commands to the
new function sata_fsl_host_stop and bind the new function to host_stop
by referring to achi.

You mean AHCI? I don't see where you reference ahci (or achi)...

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>

Doesn't this need to go into the stable trees?

drivers/ata/sata_fsl.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c
index e5838b23c9e0..30759fd1c3a2 100644
--- a/drivers/ata/sata_fsl.c
+++ b/drivers/ata/sata_fsl.c
@@ -1430,12 +1430,25 @@ static struct ata_port_operations sata_fsl_ops = {
.pmp_detach = sata_fsl_pmp_detach,
+static void sata_fsl_host_stop(struct ata_host *host)
+ struct sata_fsl_host_priv *host_priv = host->private_data;
+ iounmap(host_priv->hcr_base);
+ kfree(host_priv);
+static struct ata_port_operations sata_fsl_platform_ops = {
+ .inherits = &sata_fsl_ops,
+ .host_stop = sata_fsl_host_stop,

Why not just add it to the initializer for sata_fsl_ops?


MBR, Sergei