On Sun, Sep 09, 2018 at 11:16:33AM +0200, Greg KH wrote: > On Sun, Sep 09, 2018 at 12:56:45AM -0300, Rafael David Tinoco wrote: > > Greg, > > > > On Fri, Sep 7, 2018 at 6:41 PM Greg Kroah-Hartman > > <[email protected]> wrote: > > > > > > 4.4-stable review patch. If anyone has any objections, please let me > > > know. > > > > > > ------------------ > > > > > > From: Jann Horn <[email protected]> > > > > > > commit 5820f140edef111a9ea2ef414ab2428b8cb805b1 upstream. > > > > > > The old code would hold the userns_state_mutex indefinitely if > > > memdup_user_nul stalled due to e.g. a userfault region. Prevent that by > > > moving the memdup_user_nul in front of the mutex_lock(). > > > > > > Note: This changes the error precedence of invalid buf/count/*ppos vs > > > map already written / capabilities missing. > > > > > > Fixes: 22d917d80e84 ("userns: Rework the user_namespace adding > > > uid/gid...") > > > Cc: [email protected] > > > Signed-off-by: Jann Horn <[email protected]> > > > Acked-by: Christian Brauner <[email protected]> > > > Acked-by: Serge Hallyn <[email protected]> > > > Signed-off-by: Eric W. Biederman <[email protected]> > > > Signed-off-by: Greg Kroah-Hartman <[email protected]> > > > > > > --- > > > kernel/user_namespace.c | 22 ++++++++++------------ > > > 1 file changed, 10 insertions(+), 12 deletions(-) > > > > > > --- a/kernel/user_namespace.c > > > +++ b/kernel/user_namespace.c > > > @@ -604,7 +604,16 @@ static ssize_t map_write(struct file *fi > > > struct uid_gid_extent *extent = NULL; > > > unsigned long page = 0; > > > char *kbuf, *pos, *next_line; > > > - ssize_t ret = -EINVAL; > > > + ssize_t ret; > > > + > > > + /* Only allow < page size writes at the beginning of the file */ > > > + if ((*ppos != 0) || (count >= PAGE_SIZE)) > > > + return -EINVAL; > > > + > > > + /* Slurp in the user data */ > > > + if (copy_from_user(kbuf, buf, count)) > > > + return -EFAULT; > > > + kbuf[count] = '\0'; > > > > Naresh will soon report issues found by LKFT on user_ns for 4.4 kernel > > for this review round. > > > > selftests: mount_run_tests.sh [FAIL] > > write to /proc/self/uid_map failed: Bad address > > > > LTP: user_namespace2 1 TBROK : safe_macros.c:452: userns02.c:95: > > write(6,0x7ffc133113d0,18446744073709551615) failed: errno=EFAULT(14): > > Bad address > > > > I believe the EFAULT was caused because when changing code from > > "memdup_user_nul" to "copy_from_user", for the older kernels, you > > missed allocating the slab object for "kbuf", like memdup_user_nul() > > does. > > > > Note: This likely applies to 3.18 as well. > > > > We are finishing functional tests without this patch, but we wanted to > > make you aware right away. > > Ok, should now be fixed up, thanks for finding this and noticing it. > I've pushed out a -rc3 with the fix.
And I've fixed it up in 3.18 as well, pushing out a -rc2 with the fix. thanks, greg k-h
