[PATCH 3/4] ata: libata-core: Fix double free on error

[Niklas Cassel <cassel@kernel.org>]

If e.g. the ata_port_alloc() call in ata_host_alloc() fails, we will jump
to the err_out label, which will call devres_release_group().
devres_release_group() will trigger a call to ata_host_release().
ata_host_release() calls kfree(host), so executing the kfree(host) in
ata_host_alloc() will lead to a double free:

kernel BUG at mm/slub.c:553!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
CPU: 11 PID: 599 Comm: (udev-worker) Not tainted 6.10.0-rc5 #47
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
RIP: 0010:kfree+0x2cf/0x2f0
Code: 5d 41 5e 41 5f 5d e9 80 d6 ff ff 4d 89 f1 41 b8 01 00 00 00 48 89 d9 48 89 da
RSP: 0018:ffffc90000f377f0 EFLAGS: 00010246
RAX: ffff888112b1f2c0 RBX: ffff888112b1f2c0 RCX: ffff888112b1f320
RDX: 000000000000400b RSI: ffffffffc02c9de5 RDI: ffff888112b1f2c0
RBP: ffffc90000f37830 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc90000f37610 R11: 617461203a736b6e R12: ffffea00044ac780
R13: ffff888100046400 R14: ffffffffc02c9de5 R15: 0000000000000006
FS:  00007f2f1cabe980(0000) GS:ffff88813b380000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2f1c3acf75 CR3: 0000000111724000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
 <TASK>
 ? __die_body.cold+0x19/0x27
 ? die+0x2e/0x50
 ? do_trap+0xca/0x110
 ? do_error_trap+0x6a/0x90
 ? kfree+0x2cf/0x2f0
 ? exc_invalid_op+0x50/0x70
 ? kfree+0x2cf/0x2f0
 ? asm_exc_invalid_op+0x1a/0x20
 ? ata_host_alloc+0xf5/0x120 [libata]
 ? ata_host_alloc+0xf5/0x120 [libata]
 ? kfree+0x2cf/0x2f0
 ata_host_alloc+0xf5/0x120 [libata]
 ata_host_alloc_pinfo+0x14/0xa0 [libata]
 ahci_init_one+0x6c9/0xd20 [ahci]

Ensure that we will not call kfree(host) twice, by performing the kfree()
only if the devres_open_group() call failed.

Fixes: dafd6c496381 ("libata: ensure host is free'd on error exit paths")
Cc: stable@vger.kernel.org
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/ata/libata-core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 481baa55ebfc..e0455a182af7 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5578,8 +5578,10 @@ struct ata_host *ata_host_alloc(struct device *dev, int max_ports)
 	if (!host)
 		return NULL;
 
-	if (!devres_open_group(dev, NULL, GFP_KERNEL))
-		goto err_free;
+	if (!devres_open_group(dev, NULL, GFP_KERNEL)) {
+		kfree(host);
+		return NULL;
+	}
 
 	dr = devres_alloc(ata_devres_release, 0, GFP_KERNEL);
 	if (!dr)
@@ -5611,8 +5613,6 @@ struct ata_host *ata_host_alloc(struct device *dev, int max_ports)
 
  err_out:
 	devres_release_group(dev, NULL);
- err_free:
-	kfree(host);
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(ata_host_alloc);
-- 
2.45.2