On Sat, Jul 15, 2017 at 02:50:30AM -0500, Eric W. Biederman wrote: > >*Scratches my head* > >Is there code in v4.9 where this matters? At the time I merged this to >my knowledge there were no in kernel users that cared. Which is why I >did not cc stable in the first place. Hey Eric, We're trying to go over older commits and figure out if they should have been in -stable even though they're not marked for stable. Because of cases like these, they get to be reviewed a bunch more to verify that indeed should go into -stable, which is why you got this mail. I'll drop this patch from the queue. > >Eric > > >"Levin, Alexander (Sasha Levin)" <alexander.levin@xxxxxxxxxxx> writes: > >> From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> >> >> [ Upstream commit 75422726b0f717d67db3283c2eb5bc14fa2619c5 ] >> >> Add MS_KERNMOUNT to the flags that are passed. >> Use sget_userns and force &init_user_ns instead of calling sget so that >> even if called from a weird context the internal filesystem will be >> considered to be in the intial user namespace. >> >> Luis Ressel reported that the the failure to pass MS_KERNMOUNT into >> mount_pseudo broke his in development graphics driver that uses the >> generic drm infrastructure. I am not certain the deriver was bug >> free in it's usage of that infrastructure but since >> mount_pseudo_xattr can never be triggered by userspace it is clearer >> and less error prone, and less problematic for the code to be explicit. >> >> Reported-by: Luis Ressel <aranea@xxxxxxxx> >> Tested-by: Luis Ressel <aranea@xxxxxxxx> >> Acked-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> >> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> >> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> >> --- >> fs/libfs.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/fs/libfs.c b/fs/libfs.c >> index 48826d4da189..9588780ad43e 100644 >> --- a/fs/libfs.c >> +++ b/fs/libfs.c >> @@ -245,7 +245,8 @@ struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name, >> struct inode *root; >> struct qstr d_name = QSTR_INIT(name, strlen(name)); >> >> - s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL); >> + s = sget_userns(fs_type, NULL, set_anon_super, MS_KERNMOUNT|MS_NOUSER, >> + &init_user_ns, NULL); >> if (IS_ERR(s)) >> return ERR_CAST(s); -- Thanks, Sasha