Feedback-ID: i787e41f1:Fastmail
Date: Wed, 23 Sep 2026 10:03:20 +0200
From: Greg KH <greg@kroah.com>
To: Sasha Levin <sashal@kernel.org>
Cc: stable@vger.kernel.org, Paulo Alcantara <pc@manguebit.org>,
	Namjae Jeon <linkinjeon@kernel.org>,
	Ronnie Sahlberg <ronniesahlberg@gmail.com>,
	Shyam Prasad N <sprasad@microsoft.com>, Tom Talpey <tom@talpey.com>,
	Bharath SM <bharathsm@microsoft.com>
Subject: Re: [PATCH 6.18.y 1/3] smb: client: fix WSL reparse point uid/gid
 override
Message-ID: <2026092315-dayroom-catty-be31@gregkh>
References: <2026092249-multitude-amigo-b729@gregkh>
 <20260922194812.85938-1-sashal@kernel.org>
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In-Reply-To: <20260922194812.85938-1-sashal@kernel.org>

On Tue, Sep 22, 2026 at 03:48:10PM -0400, Sasha Levin wrote:
> From: Paulo Alcantara <pc@manguebit.org>
> 
> [ Upstream commit cd2b2b57921d4caa7875e83198bb2aa71254328b ]
> 
> wsl_to_fattr() unconditionally overwrites cf_uid/cf_gid with values
> from WSL extended attributes ($LXUID/$LXGID), ignoring the forceuid
> and forcegid mount options.
> 
> Fix this by initializing cf_uid/cf_gid to the mount defaults and
> gating the $LXUID/$LXGID EA parsing on forceuid/forcegid.
> 
> Closes: https://sashiko.dev/#/patchset/20260906190803.667489-1-pc%40manguebit.org
> Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
> Signed-off-by: Paulo Alcantara <pc@manguebit.org>
> Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
> Cc: Shyam Prasad N <sprasad@microsoft.com>
> Cc: Tom Talpey <tom@talpey.com>
> Cc: Bharath SM <bharathsm@microsoft.com>
> Cc: stable@vger.kernel.org
> 
> Backport adaptation for Linux 6.18:
> Keep the existing S_IFMT clearing from 99daf7535445 when adding the
> mount-default UID/GID initialization.  The stable branch already has
> that file-type fix, which followed this dependency upstream.
> 
> Also include the two wsl_to_fattr() mode-read conversions from
> e1aeaf79dea5 and include linux/unaligned.h directly.  These are the
> remaining context changes needed for e1253a82bb4c to apply unchanged;
> the other helper conversions are outside this target's context.
> 
> Stable-dep-of: e1253a82bb4c ("smb: client: fix fattr leaking on wsl_to_fattr() failure")
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
>  fs/smb/client/reparse.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
> index 6ec6b8c46ba22..c87b282da1ce9 100644
> --- a/fs/smb/client/reparse.c
> +++ b/fs/smb/client/reparse.c
> @@ -6,6 +6,7 @@
>  #include <linux/fs.h>
>  #include <linux/stat.h>
>  #include <linux/slab.h>
> +#include <linux/unaligned.h>
>  #include "cifsglob.h"
>  #include "smb2proto.h"
>  #include "cifsproto.h"
> @@ -1109,10 +1110,14 @@ static bool wsl_to_fattr(struct cifs_open_info_data *data,
>  			 struct cifs_sb_info *cifs_sb,
>  			 u32 tag, struct cifs_fattr *fattr)
>  {
> +	unsigned int sbflags = cifs_sb_flags(cifs_sb);
>  	struct smb2_file_full_ea_info *ea;
>  	bool have_xattr_dev = false;
>  	u32 next = 0;
>  
> +	fattr->cf_uid = cifs_sb->ctx->linux_uid;
> +	fattr->cf_gid = cifs_sb->ctx->linux_gid;
> +
>  	fattr->cf_mode &= ~S_IFMT;
>  	switch (tag) {
>  	case IO_REPARSE_TAG_LX_SYMLINK:
> @@ -1150,15 +1155,17 @@ static bool wsl_to_fattr(struct cifs_open_info_data *data,
>  		nlen = ea->ea_name_length;
>  		v = (void *)((u8 *)ea->ea_data + ea->ea_name_length + 1);
>  
> -		if (!strncmp(name, SMB2_WSL_XATTR_UID, nlen))
> -			fattr->cf_uid = wsl_make_kuid(cifs_sb, v);
> -		else if (!strncmp(name, SMB2_WSL_XATTR_GID, nlen))
> -			fattr->cf_gid = wsl_make_kgid(cifs_sb, v);
> -		else if (!strncmp(name, SMB2_WSL_XATTR_MODE, nlen)) {
> +		if (!strncmp(name, SMB2_WSL_XATTR_UID, nlen)) {
> +			if (!(sbflags & CIFS_MOUNT_OVERR_UID))
> +				fattr->cf_uid = wsl_make_kuid(cifs_sb, v);
> +		} else if (!strncmp(name, SMB2_WSL_XATTR_GID, nlen)) {
> +			if (!(sbflags & CIFS_MOUNT_OVERR_GID))
> +				fattr->cf_gid = wsl_make_kgid(cifs_sb, v);
> +		} else if (!strncmp(name, SMB2_WSL_XATTR_MODE, nlen)) {
>  			/* File type in reparse point tag and in xattr mode must match. */
> -			if (S_DT(fattr->cf_mode) != S_DT(le32_to_cpu(*(__le32 *)v)))
> +			if (S_DT(fattr->cf_mode) != S_DT(get_unaligned_le32(v)))
>  				return false;
> -			fattr->cf_mode = (umode_t)le32_to_cpu(*(__le32 *)v);
> +			fattr->cf_mode = (umode_t)get_unaligned_le32(v);
>  		} else if (!strncmp(name, SMB2_WSL_XATTR_DEV, nlen)) {
>  			fattr->cf_rdev = reparse_mkdev(v);
>  			have_xattr_dev = true;
> -- 
> 2.53.0
> 
> 

Does not apply :(