Re: FAILED: patch "[PATCH] ata: libata-core: Fix null pointer dereference on error" failed to apply to 6.9-stable tree

[Damien Le Moal <dlemoal@kernel.org>]

On 7/1/24 23:31, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 6.9-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> To reproduce the conflict and resubmit, you may use the following commands:
> 
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.9.y
> git checkout FETCH_HEAD
> git cherry-pick -x 5d92c7c566dc76d96e0e19e481d926bbe6631c1e
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024070105-falsify-surrender-babc@gregkh' --subject-prefix 'PATCH 6.9.y' HEAD^..
> 
> Possible dependencies:
> 
> 5d92c7c566dc ("ata: libata-core: Fix null pointer dereference on error")

Greg,

I am confused... This patch applies cleanly to linux-6.9.y. The procedure above
also works just fine. And the "Possible dependencies" on itself does not make
sense. Bot problem ?

> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> From 5d92c7c566dc76d96e0e19e481d926bbe6631c1e Mon Sep 17 00:00:00 2001
> From: Niklas Cassel <cassel@kernel.org>
> Date: Sat, 29 Jun 2024 14:42:11 +0200
> Subject: [PATCH] ata: libata-core: Fix null pointer dereference on error
> 
> 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
> Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> Reviewed-by: John Garry <john.g.garry@oracle.com>
> Link: https://lore.kernel.org/r/20240629124210.181537-7-cassel@kernel.org
> Signed-off-by: Niklas Cassel <cassel@kernel.org>
> 
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index efb5195da60c..bdccf4ea251a 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -5517,6 +5517,9 @@ static void ata_host_release(struct kref *kref)
>  	for (i = 0; i < host->n_ports; i++) {
>  		struct ata_port *ap = host->ports[i];
>  
> +		if (!ap)
> +			continue;
> +
>  		kfree(ap->pmp_link);
>  		kfree(ap->slave_link);
>  		kfree(ap->ncq_sense_buf);
> 

-- 
Damien Le Moal
Western Digital Research