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FAILED: patch "[PATCH] 9p: only copy valid iattrs in 9P2000.L setattr implementation" failed to apply to 4.4-stable tree

PATCH [email protected] 1 participant 1 message Jan 18, 2022

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The patch below does not apply to the 4.4-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 <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3cb6ee991496b67ee284c6895a0ba007e2d7bac3 Mon Sep 17 00:00:00 2001
From: Christian Brauner <[email protected]>
Date: Mon, 29 Nov 2021 12:44:34 +0100
Subject: [PATCH] 9p: only copy valid iattrs in 9P2000.L setattr implementation

The 9P2000.L setattr method v9fs_vfs_setattr_dotl() copies struct iattr values without checking whether they are valid causing unitialized values to be copied. The 9P2000 setattr method v9fs_vfs_setattr() method gets this right. Check whether struct iattr fields are valid first before copying in v9fs_vfs_setattr_dotl() too and make sure that all other fields are set to 0 apart from {g,u}id which should be set to INVALID_{G,U}ID. This ensure that they can be safely sent over the wire or printed for debugging later on.

Link https://lkml.kernel.org/r/[email protected] open here
Link https://lkml.kernel.org/r/000000000000a0d53f05d1c72a4c%40google.com open here
Cc Eric Van Hensbergen <[email protected]>
Cc Latchesar Ionkov <[email protected]>
Cc Dominique Martinet <[email protected]>
Cc [email protected]
Cc [email protected]
Reported-by [email protected]
Signed-off-by Christian Brauner <[email protected]>
[Dominique: do not set a/mtime with just ATTR_A/MTIME as discussed]
Signed-off-by Dominique Martinet <[email protected]>
fs/9p/vfs_inode_dotl.c +20 -9
index 7dee89ba32e7..52f8ae79db21 100644
@@ -551,7 +551,10 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
 {
 	int retval, use_dentry = 0;
 	struct p9_fid *fid = NULL;
-	struct p9_iattr_dotl p9attr;
+	struct p9_iattr_dotl p9attr = {
+		.uid = INVALID_UID,
+		.gid = INVALID_GID,
+	};
 	struct inode *inode = d_inode(dentry);
 
 	p9_debug(P9_DEBUG_VFS, "\n");

@@ -561,14 +564,22 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
 		return retval;
 
 	p9attr.valid = v9fs_mapped_iattr_valid(iattr->ia_valid);
-	p9attr.mode = iattr->ia_mode;
-	p9attr.uid = iattr->ia_uid;
-	p9attr.gid = iattr->ia_gid;
-	p9attr.size = iattr->ia_size;
-	p9attr.atime_sec = iattr->ia_atime.tv_sec;
-	p9attr.atime_nsec = iattr->ia_atime.tv_nsec;
-	p9attr.mtime_sec = iattr->ia_mtime.tv_sec;
-	p9attr.mtime_nsec = iattr->ia_mtime.tv_nsec;
+	if (iattr->ia_valid & ATTR_MODE)
+		p9attr.mode = iattr->ia_mode;
+	if (iattr->ia_valid & ATTR_UID)
+		p9attr.uid = iattr->ia_uid;
+	if (iattr->ia_valid & ATTR_GID)
+		p9attr.gid = iattr->ia_gid;
+	if (iattr->ia_valid & ATTR_SIZE)
+		p9attr.size = iattr->ia_size;
+	if (iattr->ia_valid & ATTR_ATIME_SET) {
+		p9attr.atime_sec = iattr->ia_atime.tv_sec;
+		p9attr.atime_nsec = iattr->ia_atime.tv_nsec;
+	}
+	if (iattr->ia_valid & ATTR_MTIME_SET) {
+		p9attr.mtime_sec = iattr->ia_mtime.tv_sec;
+		p9attr.mtime_nsec = iattr->ia_mtime.tv_nsec;
+	}
 
 	if (iattr->ia_valid & ATTR_FILE) {
 		fid = iattr->ia_file->private_data;