[cip-dev] CVE-2020-12770: easy backport of sg code

[cip-dev] CVE-2020-12770: easy backport of sg code

[Pavel Machek]

[-- Attachment #1.1: Type: text/plain, Size: 1720 bytes --]

Hi!

So let me investigate... Mainline fix is commit 83c6f2390040f188cc25b270b4befeb5628c1aee.

Backport for 4.19 looks really easy, and I can't see anything wrong
there:

commit c45e3bcdebb204ef1ba1d00f41fe7ed39c4dd8cd
Author: Pavel Machek <pavel@ucw.cz>
Date:   Thu May 14 23:47:42 2020 +0200

    Backport.
    
    commit 83c6f2390040f188cc25b270b4befeb5628c1aee
    ...
        scsi: sg: add sg_remove_request in sg_write
    
        If the __copy_from_user function failed we need to call
        sg_remove_request
            in sg_write.
    
     Link: https://lore.kernel.org/r/610618d9-e983-fd56-ed0f-639428343af7@huawei.com
     Acked-by: Douglas Gilbert <dgilbert@interlog.com>
     Signed-off-by: Wu Bo <wubo40@huawei.com>
     Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 8a254bb46a9b..4f00d3062bd6 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -694,8 +694,10 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
 	hp->flags = input_size;	/* structure abuse ... */
 	hp->pack_id = old_hdr.pack_id;
 	hp->usr_ptr = NULL;
-	if (__copy_from_user(cmnd, buf, cmd_size))
+	if (__copy_from_user(cmnd, buf, cmd_size)) {
+		sg_remove_request(sfp, srp);
 		return -EFAULT;
+	}
 	/*
 	 * SG_DXFER_TO_FROM_DEV is functionally equivalent to SG_DXFER_FROM_DEV,
 	 * but is is possible that the app intended SG_DXFER_TO_DEV, because there

And I don't see a problem with 4.4, either.

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[-- Attachment #1.2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

[-- Attachment #2: Type: text/plain, Size: 419 bytes --]

-=-=-=-=-=-=-=-=-=-=-=-
Links: You receive all messages sent to this group.

View/Reply Online (#4621): https://lists.cip-project.org/g/cip-dev/message/4621
Mute This Topic: https://lists.cip-project.org/mt/74215710/4520388
Group Owner: cip-dev+owner@lists.cip-project.org
Unsubscribe: https://lists.cip-project.org/g/cip-dev/leave/8129055/727948398/xyzzy  [cip-dev@archiver.kernel.org]
-=-=-=-=-=-=-=-=-=-=-=-

Re: [cip-dev] CVE-2020-12770: easy backport of sg code

[Nobuhiro Iwamatsu]

[-- Attachment #1: Type: text/plain, Size: 2331 bytes --]

Hi Pavel,

Thanks for your work.
I was also working on this.
But the same patch seems to have already been posted by Guenter Roeck.

  https://lore.kernel.org/stable/20200514150551.240275-1-linux@roeck-us.net/

Best regards,
  Nobuhiro

> -----Original Message-----
> From: cip-dev@lists.cip-project.org [mailto:cip-dev@lists.cip-project.org] On Behalf Of Pavel Machek
> Sent: Friday, May 15, 2020 6:56 AM
> To: cip-dev@lists.cip-project.org
> Subject: [cip-dev] CVE-2020-12770: easy backport of sg code
> 
> Hi!
> 
> So let me investigate... Mainline fix is commit 83c6f2390040f188cc25b270b4befeb5628c1aee.
> 
> Backport for 4.19 looks really easy, and I can't see anything wrong
> there:
> 
> commit c45e3bcdebb204ef1ba1d00f41fe7ed39c4dd8cd
> Author: Pavel Machek <pavel@ucw.cz>
> Date:   Thu May 14 23:47:42 2020 +0200
> 
>     Backport.
> 
>     commit 83c6f2390040f188cc25b270b4befeb5628c1aee
>     ...
>         scsi: sg: add sg_remove_request in sg_write
> 
>         If the __copy_from_user function failed we need to call
>         sg_remove_request
>             in sg_write.
> 
>      Link: https://lore.kernel.org/r/610618d9-e983-fd56-ed0f-639428343af7@huawei.com
>      Acked-by: Douglas Gilbert <dgilbert@interlog.com>
>      Signed-off-by: Wu Bo <wubo40@huawei.com>
>      Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
> 
> diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
> index 8a254bb46a9b..4f00d3062bd6 100644
> --- a/drivers/scsi/sg.c
> +++ b/drivers/scsi/sg.c
> @@ -694,8 +694,10 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
>  	hp->flags = input_size;	/* structure abuse ... */
>  	hp->pack_id = old_hdr.pack_id;
>  	hp->usr_ptr = NULL;
> -	if (__copy_from_user(cmnd, buf, cmd_size))
> +	if (__copy_from_user(cmnd, buf, cmd_size)) {
> +		sg_remove_request(sfp, srp);
>  		return -EFAULT;
> +	}
>  	/*
>  	 * SG_DXFER_TO_FROM_DEV is functionally equivalent to SG_DXFER_FROM_DEV,
>  	 * but is is possible that the app intended SG_DXFER_TO_DEV, because there
> 
> And I don't see a problem with 4.4, either.
> 
> Best regards,
> 									Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[-- Attachment #2: Type: text/plain, Size: 419 bytes --]

-=-=-=-=-=-=-=-=-=-=-=-
Links: You receive all messages sent to this group.

View/Reply Online (#4622): https://lists.cip-project.org/g/cip-dev/message/4622
Mute This Topic: https://lists.cip-project.org/mt/74215710/4520388
Group Owner: cip-dev+owner@lists.cip-project.org
Unsubscribe: https://lists.cip-project.org/g/cip-dev/leave/8129055/727948398/xyzzy  [cip-dev@archiver.kernel.org]
-=-=-=-=-=-=-=-=-=-=-=-