[PATCH v2 01/13] ata: libata-core: Fix null pointer dereference on error

[Niklas Cassel <cassel@kernel.org>]

If the ata_port_alloc() call in ata_host_alloc() fails,
ata_host_release() will get called.

However, the code in ata_host_release() tries to free ata_port struct
members unconditionally, which can lead to the following:

BUG: unable to handle page fault for address: 0000000000003990
PGD 0 P4D 0
Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 10 PID: 594 Comm: (udev-worker) Not tainted 6.10.0-rc5 #44
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
RIP: 0010:ata_host_release.cold+0x2f/0x6e [libata]
Code: e4 4d 63 f4 44 89 e2 48 c7 c6 90 ad 32 c0 48 c7 c7 d0 70 33 c0 49 83 c6 0e 41
RSP: 0018:ffffc90000ebb968 EFLAGS: 00010246
RAX: 0000000000000041 RBX: ffff88810fb52e78 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff88813b3218c0 RDI: ffff88813b3218c0
RBP: ffff88810fb52e40 R08: 0000000000000000 R09: 6c65725f74736f68
R10: ffffc90000ebb738 R11: 73692033203a746e R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000011 R15: 0000000000000006
FS:  00007f6cc55b9980(0000) GS:ffff88813b300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000003990 CR3: 00000001122a2000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
 <TASK>
 ? __die_body.cold+0x19/0x27
 ? page_fault_oops+0x15a/0x2f0
 ? exc_page_fault+0x7e/0x180
 ? asm_exc_page_fault+0x26/0x30
 ? ata_host_release.cold+0x2f/0x6e [libata]
 ? ata_host_release.cold+0x2f/0x6e [libata]
 release_nodes+0x35/0xb0
 devres_release_group+0x113/0x140
 ata_host_alloc+0xed/0x120 [libata]
 ata_host_alloc_pinfo+0x14/0xa0 [libata]
 ahci_init_one+0x6c9/0xd20 [ahci]

Do not access ata_port struct members unconditionally.

Fixes: 633273a3ed1c ("libata-pmp: hook PMP support and enable it")
Cc: stable@vger.kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/ata/libata-core.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index e1bf8a19b3c8..88e32f638f33 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5518,10 +5518,12 @@ static void ata_host_release(struct kref *kref)
 	for (i = 0; i < host->n_ports; i++) {
 		struct ata_port *ap = host->ports[i];
 
-		kfree(ap->pmp_link);
-		kfree(ap->slave_link);
-		kfree(ap->ncq_sense_buf);
-		kfree(ap);
+		if (ap) {
+			kfree(ap->pmp_link);
+			kfree(ap->slave_link);
+			kfree(ap->ncq_sense_buf);
+			kfree(ap);
+		}
 		host->ports[i] = NULL;
 	}
 	kfree(host);
-- 
2.45.2