Re: [PATCH v2 02/13] ata: libata-core: Fix double free on error

[Hannes Reinecke <hare@suse.de>]

On 6/26/24 20:00, Niklas Cassel wrote:
> 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
> 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 88e32f638f33..c916cbe3e099 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -5573,8 +5573,10 @@ 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)
> @@ -5606,8 +5608,6 @@ 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);
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
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