From: Christian Brauner christian.brauner@ubuntu.com
commit 3cb6ee991496b67ee284c6895a0ba007e2d7bac3 upstream.
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/20211129114434.3637938-1-brauner@kernel.org Link: https://lkml.kernel.org/r/000000000000a0d53f05d1c72a4c%40google.com Cc: Eric Van Hensbergen ericvh@gmail.com Cc: Latchesar Ionkov lucho@ionkov.net Cc: Dominique Martinet asmadeus@codewreck.org Cc: stable@kernel.org Cc: v9fs-developer@lists.sourceforge.net Reported-by: syzbot+dfac92a50024b54acaa4@syzkaller.appspotmail.com Signed-off-by: Christian Brauner christian.brauner@ubuntu.com [Dominique: do not set a/mtime with just ATTR_A/MTIME as discussed] Signed-off-by: Dominique Martinet asmadeus@codewreck.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/9p/vfs_inode_dotl.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-)
--- a/fs/9p/vfs_inode_dotl.c +++ b/fs/9p/vfs_inode_dotl.c @@ -553,7 +553,10 @@ int v9fs_vfs_setattr_dotl(struct user_na { 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"); @@ -563,14 +566,22 @@ int v9fs_vfs_setattr_dotl(struct user_na 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;