* BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
@ 2014-10-06 13:29 Andrey Wagin
2014-10-06 18:19 ` Serge E. Hallyn
0 siblings, 1 reply; 5+ messages in thread
From: Andrey Wagin @ 2014-10-06 13:29 UTC (permalink / raw)
To: linux-fsdevel, LKML
Hi All,
Here is a small program, which triggers a bug. Is it interested for someone?
root@ubuntu:/home/avagin# cat nsenter.c
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <sched.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mount.h>
int main(int argc, char **argv)
{
int fd;
fd = open("/proc/self/ns/mnt", O_RDONLY);
if (fd < 0)
return 1;
umount2("/", MNT_DETACH);
if (setns(fd, CLONE_NEWNS))
return 1;
umount2("/", MNT_DETACH);
return 0;
}
root@ubuntu:/home/avagin# gcc nsenter.c -o nsenter
root@ubuntu:/home/avagin# ./nsenter
[ 260.548301] ------------[ cut here ]------------
[ 260.550941] kernel BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
[ 260.552068] invalid opcode: 0000 [#1] SMP
[ 260.552068] Modules linked in: xt_CHECKSUM iptable_mangle xt_tcpudp
xt_addrtype xt_conntrack ipt_MASQUERADE iptable_nat nf_conntrack_ipv4
nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack bridge stp llc
dm_thin_pool dm_persistent_data dm_bufio dm_bio_prison iptable_filter
ip_tables x_tables crct10dif_pclmul crc32_pclmul ghash_clmulni_intel
binfmt_misc nfsd auth_rpcgss nfs_acl aesni_intel nfs lockd aes_x86_64
sunrpc fscache lrw gf128mul glue_helper ablk_helper cryptd serio_raw
ppdev parport_pc lp parport btrfs xor raid6_pq libcrc32c psmouse
floppy
[ 260.552068] CPU: 0 PID: 1723 Comm: nsenter Not tainted
3.13.0-30-generic #55-Ubuntu
[ 260.552068] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 260.552068] task: ffff8800376097f0 ti: ffff880074824000 task.ti:
ffff880074824000
[ 260.552068] RIP: 0010:[<ffffffff811e9483>] [<ffffffff811e9483>]
propagate_umount+0x123/0x130
[ 260.552068] RSP: 0018:ffff880074825e98 EFLAGS: 00010246
[ 260.552068] RAX: ffff88007c741140 RBX: 0000000000000002 RCX: ffff88007c741190
[ 260.552068] RDX: ffff88007c741190 RSI: ffff880074825ec0 RDI: ffff880074825ec0
[ 260.552068] RBP: ffff880074825eb0 R08: 00000000000172e0 R09: ffff88007fc172e0
[ 260.552068] R10: ffffffff811cc642 R11: ffffea0001d59000 R12: ffff88007c741140
[ 260.552068] R13: ffff88007c741140 R14: ffff88007c741140 R15: 0000000000000000
[ 260.552068] FS: 00007fd5c7e41740(0000) GS:ffff88007fc00000(0000)
knlGS:0000000000000000
[ 260.552068] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 260.552068] CR2: 00007fd5c7968050 CR3: 0000000070124000 CR4: 00000000000406f0
[ 260.552068] Stack:
[ 260.552068] 0000000000000002 0000000000000002 ffff88007c631000
ffff880074825ed8
[ 260.552068] ffffffff811dcfac ffff88007c741140 0000000000000002
ffff88007c741160
[ 260.552068] ffff880074825f38 ffffffff811dd12b ffffffff811cc642
0000000075640000
[ 260.552068] Call Trace:
[ 260.552068] [<ffffffff811dcfac>] umount_tree+0x20c/0x260
[ 260.552068] [<ffffffff811dd12b>] do_umount+0x12b/0x300
[ 260.552068] [<ffffffff811cc642>] ? final_putname+0x22/0x50
[ 260.552068] [<ffffffff811cc849>] ? putname+0x29/0x40
[ 260.552068] [<ffffffff811dd88c>] SyS_umount+0xdc/0x100
[ 260.552068] [<ffffffff8172aeff>] tracesys+0xe1/0xe6
[ 260.552068] Code: 89 50 08 48 8b 50 08 48 89 02 49 89 45 08 e9 72
ff ff ff 0f 1f 44 00 00 4c 89 e6 4c 89 e7 e8 f5 f6 ff ff 48 89 c3 e9
39 ff ff ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 66 66 66 66 90 55
b8 01
[ 260.552068] RIP [<ffffffff811e9483>] propagate_umount+0x123/0x130
[ 260.552068] RSP <ffff880074825e98>
[ 260.611451] ---[ end trace 11c33d85f1d4c652 ]---
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
2014-10-06 13:29 BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372! Andrey Wagin
@ 2014-10-06 18:19 ` Serge E. Hallyn
2014-10-06 19:30 ` Andrey Wagin
0 siblings, 1 reply; 5+ messages in thread
From: Serge E. Hallyn @ 2014-10-06 18:19 UTC (permalink / raw)
To: Andrey Wagin; +Cc: linux-fsdevel, LKML
Quoting Andrey Wagin (avagin@gmail.com):
> Hi All,
>
> Here is a small program, which triggers a bug. Is it interested for someone?
Yup, would
diff --git a/fs/namespace.c b/fs/namespace.c
index ef42d9b..ddef25d 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3046,6 +3046,9 @@ static int mntns_install(struct nsproxy *nsproxy, void *ns)
struct mnt_namespace *mnt_ns = ns;
struct path root;
+ if (mnt_ns == nsproxy->mnt_ns)
+ return 0;
+
if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
!ns_capable(current_user_ns(), CAP_SYS_CHROOT) ||
!ns_capable(current_user_ns(), CAP_SYS_ADMIN))
fix it?
> root@ubuntu:/home/avagin# cat nsenter.c
> #define _GNU_SOURCE /* See feature_test_macros(7) */
> #include <sched.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <unistd.h>
> #include <sys/mount.h>
>
> int main(int argc, char **argv)
> {
> int fd;
>
> fd = open("/proc/self/ns/mnt", O_RDONLY);
> if (fd < 0)
> return 1;
> umount2("/", MNT_DETACH);
> if (setns(fd, CLONE_NEWNS))
> return 1;
> umount2("/", MNT_DETACH);
>
> return 0;
> }
>
> root@ubuntu:/home/avagin# gcc nsenter.c -o nsenter
> root@ubuntu:/home/avagin# ./nsenter
>
>
> [ 260.548301] ------------[ cut here ]------------
> [ 260.550941] kernel BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
> [ 260.552068] invalid opcode: 0000 [#1] SMP
> [ 260.552068] Modules linked in: xt_CHECKSUM iptable_mangle xt_tcpudp
> xt_addrtype xt_conntrack ipt_MASQUERADE iptable_nat nf_conntrack_ipv4
> nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack bridge stp llc
> dm_thin_pool dm_persistent_data dm_bufio dm_bio_prison iptable_filter
> ip_tables x_tables crct10dif_pclmul crc32_pclmul ghash_clmulni_intel
> binfmt_misc nfsd auth_rpcgss nfs_acl aesni_intel nfs lockd aes_x86_64
> sunrpc fscache lrw gf128mul glue_helper ablk_helper cryptd serio_raw
> ppdev parport_pc lp parport btrfs xor raid6_pq libcrc32c psmouse
> floppy
> [ 260.552068] CPU: 0 PID: 1723 Comm: nsenter Not tainted
> 3.13.0-30-generic #55-Ubuntu
> [ 260.552068] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> [ 260.552068] task: ffff8800376097f0 ti: ffff880074824000 task.ti:
> ffff880074824000
> [ 260.552068] RIP: 0010:[<ffffffff811e9483>] [<ffffffff811e9483>]
> propagate_umount+0x123/0x130
> [ 260.552068] RSP: 0018:ffff880074825e98 EFLAGS: 00010246
> [ 260.552068] RAX: ffff88007c741140 RBX: 0000000000000002 RCX: ffff88007c741190
> [ 260.552068] RDX: ffff88007c741190 RSI: ffff880074825ec0 RDI: ffff880074825ec0
> [ 260.552068] RBP: ffff880074825eb0 R08: 00000000000172e0 R09: ffff88007fc172e0
> [ 260.552068] R10: ffffffff811cc642 R11: ffffea0001d59000 R12: ffff88007c741140
> [ 260.552068] R13: ffff88007c741140 R14: ffff88007c741140 R15: 0000000000000000
> [ 260.552068] FS: 00007fd5c7e41740(0000) GS:ffff88007fc00000(0000)
> knlGS:0000000000000000
> [ 260.552068] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 260.552068] CR2: 00007fd5c7968050 CR3: 0000000070124000 CR4: 00000000000406f0
> [ 260.552068] Stack:
> [ 260.552068] 0000000000000002 0000000000000002 ffff88007c631000
> ffff880074825ed8
> [ 260.552068] ffffffff811dcfac ffff88007c741140 0000000000000002
> ffff88007c741160
> [ 260.552068] ffff880074825f38 ffffffff811dd12b ffffffff811cc642
> 0000000075640000
> [ 260.552068] Call Trace:
> [ 260.552068] [<ffffffff811dcfac>] umount_tree+0x20c/0x260
> [ 260.552068] [<ffffffff811dd12b>] do_umount+0x12b/0x300
> [ 260.552068] [<ffffffff811cc642>] ? final_putname+0x22/0x50
> [ 260.552068] [<ffffffff811cc849>] ? putname+0x29/0x40
> [ 260.552068] [<ffffffff811dd88c>] SyS_umount+0xdc/0x100
> [ 260.552068] [<ffffffff8172aeff>] tracesys+0xe1/0xe6
> [ 260.552068] Code: 89 50 08 48 8b 50 08 48 89 02 49 89 45 08 e9 72
> ff ff ff 0f 1f 44 00 00 4c 89 e6 4c 89 e7 e8 f5 f6 ff ff 48 89 c3 e9
> 39 ff ff ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 66 66 66 66 90 55
> b8 01
> [ 260.552068] RIP [<ffffffff811e9483>] propagate_umount+0x123/0x130
> [ 260.552068] RSP <ffff880074825e98>
> [ 260.611451] ---[ end trace 11c33d85f1d4c652 ]---
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
2014-10-06 18:19 ` Serge E. Hallyn
@ 2014-10-06 19:30 ` Andrey Wagin
2014-10-06 19:44 ` Serge E. Hallyn
0 siblings, 1 reply; 5+ messages in thread
From: Andrey Wagin @ 2014-10-06 19:30 UTC (permalink / raw)
To: Serge E. Hallyn; +Cc: linux-fsdevel, LKML
2014-10-06 22:19 GMT+04:00 Serge E. Hallyn <serge@hallyn.com>:
> Quoting Andrey Wagin (avagin@gmail.com):
>> Hi All,
>>
>> Here is a small program, which triggers a bug. Is it interested for someone?
>
> Yup, would
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index ef42d9b..ddef25d 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -3046,6 +3046,9 @@ static int mntns_install(struct nsproxy *nsproxy, void *ns)
> struct mnt_namespace *mnt_ns = ns;
> struct path root;
>
> + if (mnt_ns == nsproxy->mnt_ns)
> + return 0;
> +
> if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
> !ns_capable(current_user_ns(), CAP_SYS_CHROOT) ||
> !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
>
> fix it?
Actually the bug is triggered from the second umount. I think we need
something like this:
diff --git a/fs/namespace.c b/fs/namespace.c
index 68685b2..bbcd92c 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1363,6 +1363,9 @@ static int do_umount(struct mount *mnt, int flags)
return retval;
}
+ if (mnt->mnt_parent == mnt)
+ return -EINVAL;
+
namespace_lock();
lock_mount_hash();
event++;
root@ubuntu:/home/avagin# strace ./a.out
...
open("/proc/self/ns/mnt", O_RDONLY) = 3
umount("/", MNT_DETACH) = 0
setns(3, 131072) = 0
umount("/", MNT_DETACH) = -1 EINVAL (Invalid argument)
exit_group(0) = ?
+++ exited with 0 +++
>
>> root@ubuntu:/home/avagin# cat nsenter.c
>> #define _GNU_SOURCE /* See feature_test_macros(7) */
>> #include <sched.h>
>> #include <sys/types.h>
>> #include <sys/stat.h>
>> #include <fcntl.h>
>> #include <unistd.h>
>> #include <sys/mount.h>
>>
>> int main(int argc, char **argv)
>> {
>> int fd;
>>
>> fd = open("/proc/self/ns/mnt", O_RDONLY);
>> if (fd < 0)
>> return 1;
>> umount2("/", MNT_DETACH);
>> if (setns(fd, CLONE_NEWNS))
>> return 1;
>> umount2("/", MNT_DETACH);
>>
>> return 0;
>> }
>>
>> root@ubuntu:/home/avagin# gcc nsenter.c -o nsenter
>> root@ubuntu:/home/avagin# ./nsenter
>>
>>
>> [ 260.548301] ------------[ cut here ]------------
>> [ 260.550941] kernel BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
>> [ 260.552068] invalid opcode: 0000 [#1] SMP
>> [ 260.552068] Modules linked in: xt_CHECKSUM iptable_mangle xt_tcpudp
>> xt_addrtype xt_conntrack ipt_MASQUERADE iptable_nat nf_conntrack_ipv4
>> nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack bridge stp llc
>> dm_thin_pool dm_persistent_data dm_bufio dm_bio_prison iptable_filter
>> ip_tables x_tables crct10dif_pclmul crc32_pclmul ghash_clmulni_intel
>> binfmt_misc nfsd auth_rpcgss nfs_acl aesni_intel nfs lockd aes_x86_64
>> sunrpc fscache lrw gf128mul glue_helper ablk_helper cryptd serio_raw
>> ppdev parport_pc lp parport btrfs xor raid6_pq libcrc32c psmouse
>> floppy
>> [ 260.552068] CPU: 0 PID: 1723 Comm: nsenter Not tainted
>> 3.13.0-30-generic #55-Ubuntu
>> [ 260.552068] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
>> [ 260.552068] task: ffff8800376097f0 ti: ffff880074824000 task.ti:
>> ffff880074824000
>> [ 260.552068] RIP: 0010:[<ffffffff811e9483>] [<ffffffff811e9483>]
>> propagate_umount+0x123/0x130
>> [ 260.552068] RSP: 0018:ffff880074825e98 EFLAGS: 00010246
>> [ 260.552068] RAX: ffff88007c741140 RBX: 0000000000000002 RCX: ffff88007c741190
>> [ 260.552068] RDX: ffff88007c741190 RSI: ffff880074825ec0 RDI: ffff880074825ec0
>> [ 260.552068] RBP: ffff880074825eb0 R08: 00000000000172e0 R09: ffff88007fc172e0
>> [ 260.552068] R10: ffffffff811cc642 R11: ffffea0001d59000 R12: ffff88007c741140
>> [ 260.552068] R13: ffff88007c741140 R14: ffff88007c741140 R15: 0000000000000000
>> [ 260.552068] FS: 00007fd5c7e41740(0000) GS:ffff88007fc00000(0000)
>> knlGS:0000000000000000
>> [ 260.552068] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [ 260.552068] CR2: 00007fd5c7968050 CR3: 0000000070124000 CR4: 00000000000406f0
>> [ 260.552068] Stack:
>> [ 260.552068] 0000000000000002 0000000000000002 ffff88007c631000
>> ffff880074825ed8
>> [ 260.552068] ffffffff811dcfac ffff88007c741140 0000000000000002
>> ffff88007c741160
>> [ 260.552068] ffff880074825f38 ffffffff811dd12b ffffffff811cc642
>> 0000000075640000
>> [ 260.552068] Call Trace:
>> [ 260.552068] [<ffffffff811dcfac>] umount_tree+0x20c/0x260
>> [ 260.552068] [<ffffffff811dd12b>] do_umount+0x12b/0x300
>> [ 260.552068] [<ffffffff811cc642>] ? final_putname+0x22/0x50
>> [ 260.552068] [<ffffffff811cc849>] ? putname+0x29/0x40
>> [ 260.552068] [<ffffffff811dd88c>] SyS_umount+0xdc/0x100
>> [ 260.552068] [<ffffffff8172aeff>] tracesys+0xe1/0xe6
>> [ 260.552068] Code: 89 50 08 48 8b 50 08 48 89 02 49 89 45 08 e9 72
>> ff ff ff 0f 1f 44 00 00 4c 89 e6 4c 89 e7 e8 f5 f6 ff ff 48 89 c3 e9
>> 39 ff ff ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 66 66 66 66 90 55
>> b8 01
>> [ 260.552068] RIP [<ffffffff811e9483>] propagate_umount+0x123/0x130
>> [ 260.552068] RSP <ffff880074825e98>
>> [ 260.611451] ---[ end trace 11c33d85f1d4c652 ]---
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
2014-10-06 19:30 ` Andrey Wagin
@ 2014-10-06 19:44 ` Serge E. Hallyn
2014-10-06 19:50 ` Andrey Wagin
0 siblings, 1 reply; 5+ messages in thread
From: Serge E. Hallyn @ 2014-10-06 19:44 UTC (permalink / raw)
To: Andrey Wagin; +Cc: Serge E. Hallyn, linux-fsdevel, LKML
Quoting Andrey Wagin (avagin@gmail.com):
> 2014-10-06 22:19 GMT+04:00 Serge E. Hallyn <serge@hallyn.com>:
> > Quoting Andrey Wagin (avagin@gmail.com):
> >> Hi All,
> >>
> >> Here is a small program, which triggers a bug. Is it interested for someone?
> >
> > Yup, would
> >
> > diff --git a/fs/namespace.c b/fs/namespace.c
> > index ef42d9b..ddef25d 100644
> > --- a/fs/namespace.c
> > +++ b/fs/namespace.c
> > @@ -3046,6 +3046,9 @@ static int mntns_install(struct nsproxy *nsproxy, void *ns)
> > struct mnt_namespace *mnt_ns = ns;
> > struct path root;
> >
> > + if (mnt_ns == nsproxy->mnt_ns)
> > + return 0;
> > +
> > if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
> > !ns_capable(current_user_ns(), CAP_SYS_CHROOT) ||
> > !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
> >
> > fix it?
>
> Actually the bug is triggered from the second umount. I think we need
Oh, I see.
> something like this:
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 68685b2..bbcd92c 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -1363,6 +1363,9 @@ static int do_umount(struct mount *mnt, int flags)
> return retval;
> }
>
> + if (mnt->mnt_parent == mnt)
looks good (or the equivalent mnt_has_parent(mnt)). Have you tested that
this prevents your test program from causing a crash?
> + return -EINVAL;
> +
> namespace_lock();
> lock_mount_hash();
> event++;
>
> root@ubuntu:/home/avagin# strace ./a.out
> ...
> open("/proc/self/ns/mnt", O_RDONLY) = 3
> umount("/", MNT_DETACH) = 0
> setns(3, 131072) = 0
> umount("/", MNT_DETACH) = -1 EINVAL (Invalid argument)
> exit_group(0) = ?
> +++ exited with 0 +++
>
> >
> >> root@ubuntu:/home/avagin# cat nsenter.c
> >> #define _GNU_SOURCE /* See feature_test_macros(7) */
> >> #include <sched.h>
> >> #include <sys/types.h>
> >> #include <sys/stat.h>
> >> #include <fcntl.h>
> >> #include <unistd.h>
> >> #include <sys/mount.h>
> >>
> >> int main(int argc, char **argv)
> >> {
> >> int fd;
> >>
> >> fd = open("/proc/self/ns/mnt", O_RDONLY);
> >> if (fd < 0)
> >> return 1;
> >> umount2("/", MNT_DETACH);
> >> if (setns(fd, CLONE_NEWNS))
> >> return 1;
> >> umount2("/", MNT_DETACH);
> >>
> >> return 0;
> >> }
> >>
> >> root@ubuntu:/home/avagin# gcc nsenter.c -o nsenter
> >> root@ubuntu:/home/avagin# ./nsenter
> >>
> >>
> >> [ 260.548301] ------------[ cut here ]------------
> >> [ 260.550941] kernel BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
> >> [ 260.552068] invalid opcode: 0000 [#1] SMP
> >> [ 260.552068] Modules linked in: xt_CHECKSUM iptable_mangle xt_tcpudp
> >> xt_addrtype xt_conntrack ipt_MASQUERADE iptable_nat nf_conntrack_ipv4
> >> nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack bridge stp llc
> >> dm_thin_pool dm_persistent_data dm_bufio dm_bio_prison iptable_filter
> >> ip_tables x_tables crct10dif_pclmul crc32_pclmul ghash_clmulni_intel
> >> binfmt_misc nfsd auth_rpcgss nfs_acl aesni_intel nfs lockd aes_x86_64
> >> sunrpc fscache lrw gf128mul glue_helper ablk_helper cryptd serio_raw
> >> ppdev parport_pc lp parport btrfs xor raid6_pq libcrc32c psmouse
> >> floppy
> >> [ 260.552068] CPU: 0 PID: 1723 Comm: nsenter Not tainted
> >> 3.13.0-30-generic #55-Ubuntu
> >> [ 260.552068] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> >> [ 260.552068] task: ffff8800376097f0 ti: ffff880074824000 task.ti:
> >> ffff880074824000
> >> [ 260.552068] RIP: 0010:[<ffffffff811e9483>] [<ffffffff811e9483>]
> >> propagate_umount+0x123/0x130
> >> [ 260.552068] RSP: 0018:ffff880074825e98 EFLAGS: 00010246
> >> [ 260.552068] RAX: ffff88007c741140 RBX: 0000000000000002 RCX: ffff88007c741190
> >> [ 260.552068] RDX: ffff88007c741190 RSI: ffff880074825ec0 RDI: ffff880074825ec0
> >> [ 260.552068] RBP: ffff880074825eb0 R08: 00000000000172e0 R09: ffff88007fc172e0
> >> [ 260.552068] R10: ffffffff811cc642 R11: ffffea0001d59000 R12: ffff88007c741140
> >> [ 260.552068] R13: ffff88007c741140 R14: ffff88007c741140 R15: 0000000000000000
> >> [ 260.552068] FS: 00007fd5c7e41740(0000) GS:ffff88007fc00000(0000)
> >> knlGS:0000000000000000
> >> [ 260.552068] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >> [ 260.552068] CR2: 00007fd5c7968050 CR3: 0000000070124000 CR4: 00000000000406f0
> >> [ 260.552068] Stack:
> >> [ 260.552068] 0000000000000002 0000000000000002 ffff88007c631000
> >> ffff880074825ed8
> >> [ 260.552068] ffffffff811dcfac ffff88007c741140 0000000000000002
> >> ffff88007c741160
> >> [ 260.552068] ffff880074825f38 ffffffff811dd12b ffffffff811cc642
> >> 0000000075640000
> >> [ 260.552068] Call Trace:
> >> [ 260.552068] [<ffffffff811dcfac>] umount_tree+0x20c/0x260
> >> [ 260.552068] [<ffffffff811dd12b>] do_umount+0x12b/0x300
> >> [ 260.552068] [<ffffffff811cc642>] ? final_putname+0x22/0x50
> >> [ 260.552068] [<ffffffff811cc849>] ? putname+0x29/0x40
> >> [ 260.552068] [<ffffffff811dd88c>] SyS_umount+0xdc/0x100
> >> [ 260.552068] [<ffffffff8172aeff>] tracesys+0xe1/0xe6
> >> [ 260.552068] Code: 89 50 08 48 8b 50 08 48 89 02 49 89 45 08 e9 72
> >> ff ff ff 0f 1f 44 00 00 4c 89 e6 4c 89 e7 e8 f5 f6 ff ff 48 89 c3 e9
> >> 39 ff ff ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 66 66 66 66 90 55
> >> b8 01
> >> [ 260.552068] RIP [<ffffffff811e9483>] propagate_umount+0x123/0x130
> >> [ 260.552068] RSP <ffff880074825e98>
> >> [ 260.611451] ---[ end trace 11c33d85f1d4c652 ]---
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at http://vger.kernel.org/majordomo-info.html
> >> Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
2014-10-06 19:44 ` Serge E. Hallyn
@ 2014-10-06 19:50 ` Andrey Wagin
0 siblings, 0 replies; 5+ messages in thread
From: Andrey Wagin @ 2014-10-06 19:50 UTC (permalink / raw)
To: Serge E. Hallyn; +Cc: linux-fsdevel, LKML
2014-10-06 23:44 GMT+04:00 Serge E. Hallyn <serge@hallyn.com>:
> Quoting Andrey Wagin (avagin@gmail.com):
>> 2014-10-06 22:19 GMT+04:00 Serge E. Hallyn <serge@hallyn.com>:
>> > Quoting Andrey Wagin (avagin@gmail.com):
>> >> Hi All,
>> >>
>> >> Here is a small program, which triggers a bug. Is it interested for someone?
>> >
>> > Yup, would
>> >
>> > diff --git a/fs/namespace.c b/fs/namespace.c
>> > index ef42d9b..ddef25d 100644
>> > --- a/fs/namespace.c
>> > +++ b/fs/namespace.c
>> > @@ -3046,6 +3046,9 @@ static int mntns_install(struct nsproxy *nsproxy, void *ns)
>> > struct mnt_namespace *mnt_ns = ns;
>> > struct path root;
>> >
>> > + if (mnt_ns == nsproxy->mnt_ns)
>> > + return 0;
>> > +
>> > if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
>> > !ns_capable(current_user_ns(), CAP_SYS_CHROOT) ||
>> > !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
>> >
>> > fix it?
>>
>> Actually the bug is triggered from the second umount. I think we need
>
> Oh, I see.
>
>> something like this:
>> diff --git a/fs/namespace.c b/fs/namespace.c
>> index 68685b2..bbcd92c 100644
>> --- a/fs/namespace.c
>> +++ b/fs/namespace.c
>> @@ -1363,6 +1363,9 @@ static int do_umount(struct mount *mnt, int flags)
>> return retval;
>> }
>>
>> + if (mnt->mnt_parent == mnt)
>
> looks good (or the equivalent mnt_has_parent(mnt)). Have you tested that
> this prevents your test program from causing a crash?
Yes, I have. Look the strace output below. Today here is too late for
sending a proper patch.
>
>> + return -EINVAL;
>> +
>> namespace_lock();
>> lock_mount_hash();
>> event++;
>>
>> root@ubuntu:/home/avagin# strace ./a.out
>> ...
>> open("/proc/self/ns/mnt", O_RDONLY) = 3
>> umount("/", MNT_DETACH) = 0
>> setns(3, 131072) = 0
>> umount("/", MNT_DETACH) = -1 EINVAL (Invalid argument)
>> exit_group(0) = ?
>> +++ exited with 0 +++
>>
>> >
>> >> root@ubuntu:/home/avagin# cat nsenter.c
>> >> #define _GNU_SOURCE /* See feature_test_macros(7) */
>> >> #include <sched.h>
>> >> #include <sys/types.h>
>> >> #include <sys/stat.h>
>> >> #include <fcntl.h>
>> >> #include <unistd.h>
>> >> #include <sys/mount.h>
>> >>
>> >> int main(int argc, char **argv)
>> >> {
>> >> int fd;
>> >>
>> >> fd = open("/proc/self/ns/mnt", O_RDONLY);
>> >> if (fd < 0)
>> >> return 1;
>> >> umount2("/", MNT_DETACH);
>> >> if (setns(fd, CLONE_NEWNS))
>> >> return 1;
>> >> umount2("/", MNT_DETACH);
>> >>
>> >> return 0;
>> >> }
>> >>
>> >> root@ubuntu:/home/avagin# gcc nsenter.c -o nsenter
>> >> root@ubuntu:/home/avagin# ./nsenter
>> >>
>> >>
>> >> [ 260.548301] ------------[ cut here ]------------
>> >> [ 260.550941] kernel BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
>> >> [ 260.552068] invalid opcode: 0000 [#1] SMP
>> >> [ 260.552068] Modules linked in: xt_CHECKSUM iptable_mangle xt_tcpudp
>> >> xt_addrtype xt_conntrack ipt_MASQUERADE iptable_nat nf_conntrack_ipv4
>> >> nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack bridge stp llc
>> >> dm_thin_pool dm_persistent_data dm_bufio dm_bio_prison iptable_filter
>> >> ip_tables x_tables crct10dif_pclmul crc32_pclmul ghash_clmulni_intel
>> >> binfmt_misc nfsd auth_rpcgss nfs_acl aesni_intel nfs lockd aes_x86_64
>> >> sunrpc fscache lrw gf128mul glue_helper ablk_helper cryptd serio_raw
>> >> ppdev parport_pc lp parport btrfs xor raid6_pq libcrc32c psmouse
>> >> floppy
>> >> [ 260.552068] CPU: 0 PID: 1723 Comm: nsenter Not tainted
>> >> 3.13.0-30-generic #55-Ubuntu
>> >> [ 260.552068] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
>> >> [ 260.552068] task: ffff8800376097f0 ti: ffff880074824000 task.ti:
>> >> ffff880074824000
>> >> [ 260.552068] RIP: 0010:[<ffffffff811e9483>] [<ffffffff811e9483>]
>> >> propagate_umount+0x123/0x130
>> >> [ 260.552068] RSP: 0018:ffff880074825e98 EFLAGS: 00010246
>> >> [ 260.552068] RAX: ffff88007c741140 RBX: 0000000000000002 RCX: ffff88007c741190
>> >> [ 260.552068] RDX: ffff88007c741190 RSI: ffff880074825ec0 RDI: ffff880074825ec0
>> >> [ 260.552068] RBP: ffff880074825eb0 R08: 00000000000172e0 R09: ffff88007fc172e0
>> >> [ 260.552068] R10: ffffffff811cc642 R11: ffffea0001d59000 R12: ffff88007c741140
>> >> [ 260.552068] R13: ffff88007c741140 R14: ffff88007c741140 R15: 0000000000000000
>> >> [ 260.552068] FS: 00007fd5c7e41740(0000) GS:ffff88007fc00000(0000)
>> >> knlGS:0000000000000000
>> >> [ 260.552068] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> >> [ 260.552068] CR2: 00007fd5c7968050 CR3: 0000000070124000 CR4: 00000000000406f0
>> >> [ 260.552068] Stack:
>> >> [ 260.552068] 0000000000000002 0000000000000002 ffff88007c631000
>> >> ffff880074825ed8
>> >> [ 260.552068] ffffffff811dcfac ffff88007c741140 0000000000000002
>> >> ffff88007c741160
>> >> [ 260.552068] ffff880074825f38 ffffffff811dd12b ffffffff811cc642
>> >> 0000000075640000
>> >> [ 260.552068] Call Trace:
>> >> [ 260.552068] [<ffffffff811dcfac>] umount_tree+0x20c/0x260
>> >> [ 260.552068] [<ffffffff811dd12b>] do_umount+0x12b/0x300
>> >> [ 260.552068] [<ffffffff811cc642>] ? final_putname+0x22/0x50
>> >> [ 260.552068] [<ffffffff811cc849>] ? putname+0x29/0x40
>> >> [ 260.552068] [<ffffffff811dd88c>] SyS_umount+0xdc/0x100
>> >> [ 260.552068] [<ffffffff8172aeff>] tracesys+0xe1/0xe6
>> >> [ 260.552068] Code: 89 50 08 48 8b 50 08 48 89 02 49 89 45 08 e9 72
>> >> ff ff ff 0f 1f 44 00 00 4c 89 e6 4c 89 e7 e8 f5 f6 ff ff 48 89 c3 e9
>> >> 39 ff ff ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 66 66 66 66 90 55
>> >> b8 01
>> >> [ 260.552068] RIP [<ffffffff811e9483>] propagate_umount+0x123/0x130
>> >> [ 260.552068] RSP <ffff880074825e98>
>> >> [ 260.611451] ---[ end trace 11c33d85f1d4c652 ]---
>> >> --
>> >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> >> the body of a message to majordomo@vger.kernel.org
>> >> More majordomo info at http://vger.kernel.org/majordomo-info.html
>> >> Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2014-10-06 19:51 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-10-06 13:29 BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372! Andrey Wagin
2014-10-06 18:19 ` Serge E. Hallyn
2014-10-06 19:30 ` Andrey Wagin
2014-10-06 19:44 ` Serge E. Hallyn
2014-10-06 19:50 ` Andrey Wagin
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