CVE-2022-49826

In the Linux kernel, the following vulnerability has been resolved:

ata: libata-transport: fix double ata_host_put() in ata_tport_add()

In the error path in ata_tport_add(), when calling put_device(), ata_tport_release() is called, it will put the refcount of 'ap->host'.

And then ata_host_put() is called again, the refcount is decreased to 0, ata_host_release() is called, all ports are freed and set to null.

When unbinding the device after failure, ata_host_stop() is called to release the resources, it leads a null-ptr-deref(), because all the ports all freed and null.

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008 CPU: 7 PID: 18671 Comm: modprobe Kdump: loaded Tainted: G E 6.1.0-rc3+ #8 pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : ata_host_stop+0x3c/0x84 [libata] lr : release_nodes+0x64/0xd0 Call trace: ata_host_stop+0x3c/0x84 [libata] release_nodes+0x64/0xd0 devres_release_all+0xbc/0x1b0 device_unbind_cleanup+0x20/0x70 really_probe+0x158/0x320 __driver_probe_device+0x84/0x120 driver_probe_device+0x44/0x120 __driver_attach+0xb4/0x220 bus_for_each_dev+0x78/0xdc driver_attach+0x2c/0x40 bus_add_driver+0x184/0x240 driver_register+0x80/0x13c __pci_register_driver+0x4c/0x60 ahci_pci_driver_init+0x30/0x1000 [ahci]

Fix this by removing redundant ata_host_put() in the error path.

Null pointer dereference in libata-transport.c due to double ata_host_put(). A race condition in ata_tport_add() leads to a double ata_host_put() during error handling, resulting in premature deallocation of the ata_host structure. Subsequent calls like ata_host_stop() dereference freed memory, leading to a kernel crash. This vulnerability may allow a local privileged user (e.g., via module load/unload operations) to trigger a denial of service (DoS) via kernel panic. No data leak or privilege escalation is possible.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.