On 6/26/24 20:00, Niklas Cassel wrote:
Commit f31871951b38 ("libata: separate out ata_host_alloc() and
ata_host_register()") added ata_host_alloc(), where the API allowed
a LLD to overallocate the number of ports supplied to ata_host_alloc(),
as long as the LLD decreased host->n_ports before calling
ata_host_register().
However, this functionally has never ever been used by a single LLD.
Because of the current API design, the assignment of ap->print_id is
deferred until registration time, which is bad, because that means that
the ata_port_*() print functions cannot be used by a LLD until after
registration time, which means that a LLD is forced to use a print
function that is non-port specific, even for a port specific error.
Remove the support for decreasing the number of ports, such that it will
be possible to assign ap->print_id earlier.
Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx>
---
drivers/ata/libata-core.c | 24 ++++++++++--------------
include/linux/libata.h | 2 +-
2 files changed, 11 insertions(+), 15 deletions(-)
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 591020ea8989..a213a9c0d0a5 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5550,24 +5550,19 @@ EXPORT_SYMBOL_GPL(ata_host_put);
/**
* ata_host_alloc - allocate and init basic ATA host resources
* @dev: generic device this host is associated with
- * @max_ports: maximum number of ATA ports associated with this host
+ * @n_ports: the number of ATA ports associated with this host
*
* Allocate and initialize basic ATA host resources. LLD calls
* this function to allocate a host, initializes it fully and
* attaches it using ata_host_register().
*
- * @max_ports ports are allocated and host->n_ports is
- * initialized to @max_ports. The caller is allowed to decrease
- * host->n_ports before calling ata_host_register(). The unused
- * ports will be automatically freed on registration.
- *
* RETURNS:
* Allocate ATA host on success, NULL on failure.
*
* LOCKING:
* Inherited from calling layer (may sleep).
*/
-struct ata_host *ata_host_alloc(struct device *dev, int max_ports)
+struct ata_host *ata_host_alloc(struct device *dev, int n_ports)
{
struct ata_host *host;
size_t sz;
@@ -5575,7 +5570,7 @@ struct ata_host *ata_host_alloc(struct device *dev, int max_ports)
void *dr;
/* alloc a container for our list of ATA ports (buses) */
- sz = sizeof(struct ata_host) + (max_ports + 1) * sizeof(void *);
+ sz = sizeof(struct ata_host) + (n_ports + 1) * sizeof(void *);
host = kzalloc(sz, GFP_KERNEL);
if (!host)
return NULL;
@@ -5595,11 +5590,11 @@ struct ata_host *ata_host_alloc(struct device *dev, int max_ports)
spin_lock_init(&host->lock);
mutex_init(&host->eh_mutex);
host->dev = dev;
- host->n_ports = max_ports;
+ host->n_ports = n_ports;
kref_init(&host->kref);
/* allocate ports bound to this host */
- for (i = 0; i < max_ports; i++) {
+ for (i = 0; i < n_ports; i++) {
struct ata_port *ap;
ap = ata_port_alloc(host);
@@ -5908,12 +5903,13 @@ int ata_host_register(struct ata_host *host, const struct scsi_host_template *sh
return -EINVAL;
}
- /* Blow away unused ports. This happens when LLD can't
- * determine the exact number of ports to allocate at
- * allocation time.
+ /*
+ * For a driver using ata_host_register(), the ports are allocated by
+ * ata_host_alloc(), which also allocates the host->ports array.
+ * The number of array elements must match host->n_ports.
*/
for (i = host->n_ports; host->ports[i]; i++)
- kfree(host->ports[i]);
+ WARN_ON(host->ports[i]);
What a patently ugly check.
So you are relying on the caller to have zeroed the memory upfront.
But what happens if the caller allocated n_ports, zeroed the memory up
to that point, and then filled in all 'ports' slots?
ports[n_ports - 1] is set to a pointer, but ports[n_ports] is _not_
allocated, and there is no guarantee it'll be zero.
Causing a memory overrun and all sorts of things.
This needs to go, as it's now pointless anyway.
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich
