Re: [next]: LTP: getxattr05.c:97: TFAIL: unshare(CLONE_NEWUSER) failed: ENOSPC (28)

From: Anders Roxell
Date: Wed Jan 12 2022 - 10:56:45 EST

On Wed, 12 Jan 2022 at 15:28, Alexey Gladkov <legion@xxxxxxxxxx> wrote:
>
> On Wed, Jan 12, 2022 at 03:14:45PM +0100, Alexey Gladkov wrote:
> > On Wed, Jan 12, 2022 at 03:02:54PM +0100, Christian Brauner wrote:
> > > On Wed, Jan 12, 2022 at 02:22:42PM +0100, Anders Roxell wrote:
> > > > On Wed, 12 Jan 2022 at 14:18, Christian Brauner
> > > > <christian.brauner@xxxxxxxxxx> wrote:
> > > > >
> > > > > On Wed, Jan 12, 2022 at 05:15:37PM +0530, Naresh Kamboju wrote:
> > > > > > While testing LTP syscalls with Linux next 20220110 (and till date 20220112)
> > > > > > on x86_64, i386, arm and arm64 the following tests failed.
> > > > > >
> > > > > > tst_test.c:1365: TINFO: Timeout per run is 0h 15m 00s
> > > > > > getxattr05.c:87: TPASS: Got same data when acquiring the value of
> > > > > > system.posix_acl_access twice
> > > > > > getxattr05.c:97: TFAIL: unshare(CLONE_NEWUSER) failed: ENOSPC (28)
> > > > > > tst_test.c:391: TBROK: Invalid child (13545) exit value 1
> > > > > >
> > > > > > fanotify17.c:176: TINFO: Test #1: Global groups limit in privileged user ns
> > > > > > fanotify17.c:155: TFAIL: unshare(CLONE_NEWUSER) failed: ENOSPC (28)
> > > > > > tst_test.c:391: TBROK: Invalid child (14739) exit value 1
> > > > > >
> > > > > > sendto03.c:48: TBROK: unshare(268435456) failed: ENOSPC (28)
> > > > > >
> > > > > > setsockopt05.c:45: TBROK: unshare(268435456) failed: ENOSPC (28)
> > > > > >
> > > > > > strace output:
> > > > > > --------------
> > > > > > [pid 481] wait4(-1, 0x7fff52f5ae8c, 0, NULL) = -1 ECHILD (No child processes)
> > > > > > [pid 481] clone(child_stack=NULL,
> > > > > > flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD,
> > > > > > child_tidptr=0x7f3af0fa7a10) = 483
> > > > > > strace: Process 483 attached
> > > > > > [pid 481] wait4(-1, <unfinished ...>
> > > > > > [pid 483] unshare(CLONE_NEWUSER) = -1 ENOSPC (No space left on device)
> > > > >
> > > > > This looks like another regression in the ucount code. Reverting the
> > > > > following commit fixes it and makes the getxattr05 test work again:
> > > > >
> > > > > commit 0315b634f933b0f12cfa82660322f6186c1aa0f4
> > > > > Author: Alexey Gladkov <legion@xxxxxxxxxx>
> > > > > Date: Fri Dec 17 15:48:23 2021 +0100
> > > > >
> > > > > ucounts: Split rlimit and ucount values and max values
> > > > >
> > > > > Since the semantics of maximum rlimit values are different, it would be
> > > > > better not to mix ucount and rlimit values. This will prevent the error
> > > > > of using inc_count/dec_ucount for rlimit parameters.
> > > > >
> > > > > This patch also renames the functions to emphasize the lack of
> > > > > connection between rlimit and ucount.
> > > > >
> > > > > v2:
> > > > > - Fix the array-index-out-of-bounds that was found by the lkp project.
> > > > >
> > > > > Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
> > > > > Signed-off-by: Alexey Gladkov <legion@xxxxxxxxxx>
> > > > > Link: https://lkml.kernel.org/r/73ea569042babda5cee2092423da85027ceb471f.1639752364.git.legion@xxxxxxxxxx
> > > > > Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> > > > >
> > > > > The issue only surfaces if /proc/sys/user/max_user_namespaces is
> > > > > actually written to.
> > > >
> > > > I did a git bisect and that pointed me to this patch too.
> > >
> > > Uhm, doesn't this want to be:
> >
> > Yes. I miss it. I tried not to mix the logic, but I myself stepped on this
> > problem.
>
> It should be fixed in the four places:
>
> diff --git a/kernel/ucount.c b/kernel/ucount.c
> index 22070f004e97..5c373a453f43 100644
> --- a/kernel/ucount.c
> +++ b/kernel/ucount.c
> @@ -264,7 +264,7 @@ long inc_rlimit_ucounts(struct ucounts *ucounts, enum rlimit_type type, long v)
> long ret = 0;
>
> for (iter = ucounts; iter; iter = iter->ns->ucounts) {
> - long new = atomic_long_add_return(v, &iter->ucount[type]);
> + long new = atomic_long_add_return(v, &iter->rlimit[type]);
> if (new < 0 || new > max)
> ret = LONG_MAX;
> else if (iter == ucounts)
> @@ -279,7 +279,7 @@ bool dec_rlimit_ucounts(struct ucounts *ucounts, enum rlimit_type type, long v)
> struct ucounts *iter;
> long new = -1; /* Silence compiler warning */
> for (iter = ucounts; iter; iter = iter->ns->ucounts) {
> - long dec = atomic_long_sub_return(v, &iter->ucount[type]);
> + long dec = atomic_long_sub_return(v, &iter->rlimit[type]);
> WARN_ON_ONCE(dec < 0);
> if (iter == ucounts)
> new = dec;
> @@ -292,7 +292,7 @@ static void do_dec_rlimit_put_ucounts(struct ucounts *ucounts,
> {
> struct ucounts *iter, *next;
> for (iter = ucounts; iter != last; iter = next) {
> - long dec = atomic_long_sub_return(1, &iter->ucount[type]);
> + long dec = atomic_long_sub_return(1, &iter->rlimit[type]);
> WARN_ON_ONCE(dec < 0);
> next = iter->ns->ucounts;
> if (dec == 0)
> @@ -313,7 +313,7 @@ long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum rlimit_type type)
> long dec, ret = 0;
>
> for (iter = ucounts; iter; iter = iter->ns->ucounts) {
> - long new = atomic_long_add_return(1, &iter->ucount[type]);
> + long new = atomic_long_add_return(1, &iter->rlimit[type]);
> if (new < 0 || new > max)
> goto unwind;
> if (iter == ucounts)
> @@ -330,7 +330,7 @@ long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum rlimit_type type)
> }
> return ret;
> dec_unwind:
> - dec = atomic_long_sub_return(1, &iter->ucount[type]);
> + dec = atomic_long_sub_return(1, &iter->rlimit[type]);
> WARN_ON_ONCE(dec < 0);
> unwind:
> do_dec_rlimit_put_ucounts(ucounts, iter, type);
>

Thank you for the fix.
I applied this patch and built and ran it in qemu for arm64 and x86.
'./runltp -s getxattr05' passed on both architectures.

Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>


Cheers,
Anders