kernel/ipc, branch linux-3.4.y

Initialize msg/shm IPC objects before doing ipc_addid()

2016-03-21T01:17:56Z

commit b9a532277938798b53178d5a66af6e2915cb27cf upstream. As reported by Dmitry Vyukov, we really shouldn't do ipc_addid() before having initialized the IPC object state. Yes, we initialize the IPC object in a locked state, but with all the lockless RCU lookup work, that IPC object lock no longer means that the state cannot be seen. We already did this for the IPC semaphore code (see commit e8577d1f0329: "ipc/sem.c: fully initialize sem_array before making it visible") but we clearly forgot about msg and shm. Reported-by: Dmitry Vyukov Cc: Manfred Spraul Cc: Davidlohr Bueso Signed-off-by: Linus Torvalds [lizf: Backported to 3.4: adjust context] Signed-off-by: Zefan Li

ipc,sem: fix use after free on IPC_RMID after a task using same semaphore set exits

2016-03-21T01:17:52Z

commit 602b8593d2b4138c10e922eeaafe306f6b51817b upstream. The current semaphore code allows a potential use after free: in exit_sem we may free the task's sem_undo_list while there is still another task looping through the same semaphore set and cleaning the sem_undo list at freeary function (the task called IPC_RMID for the same semaphore set). For example, with a test program [1] running which keeps forking a lot of processes (which then do a semop call with SEM_UNDO flag), and with the parent right after removing the semaphore set with IPC_RMID, and a kernel built with CONFIG_SLAB, CONFIG_SLAB_DEBUG and CONFIG_DEBUG_SPINLOCK, you can easily see something like the following in the kernel log: Slab corruption (Not tainted): kmalloc-64 start=ffff88003b45c1c0, len=64 000: 6b 6b 6b 6b 6b 6b 6b 6b 00 6b 6b 6b 6b 6b 6b 6b kkkkkkkk.kkkkkkk 010: ff ff ff ff 6b 6b 6b 6b ff ff ff ff ff ff ff ff ....kkkk........ Prev obj: start=ffff88003b45c180, len=64 000: 00 00 00 00 ad 4e ad de ff ff ff ff 5a 5a 5a 5a .....N......ZZZZ 010: ff ff ff ff ff ff ff ff c0 fb 01 37 00 88 ff ff ...........7.... Next obj: start=ffff88003b45c200, len=64 000: 00 00 00 00 ad 4e ad de ff ff ff ff 5a 5a 5a 5a .....N......ZZZZ 010: ff ff ff ff ff ff ff ff 68 29 a7 3c 00 88 ff ff ........h).<.... BUG: spinlock wrong CPU on CPU#2, test/18028 general protection fault: 0000 [#1] SMP Modules linked in: 8021q mrp garp stp llc nf_conntrack_ipv4 nf_defrag_ipv4 ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables binfmt_misc ppdev input_leds joydev parport_pc parport floppy serio_raw virtio_balloon virtio_rng virtio_console virtio_net iosf_mbi crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcspkr qxl ttm drm_kms_helper drm snd_hda_codec_generic i2c_piix4 snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer snd soundcore crc32c_intel virtio_pci virtio_ring virtio pata_acpi ata_generic [last unloaded: speedstep_lib] CPU: 2 PID: 18028 Comm: test Not tainted 4.2.0-rc5+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014 RIP: spin_dump+0x53/0xc0 Call Trace: spin_bug+0x30/0x40 do_raw_spin_unlock+0x71/0xa0 _raw_spin_unlock+0xe/0x10 freeary+0x82/0x2a0 ? _raw_spin_lock+0xe/0x10 semctl_down.clone.0+0xce/0x160 ? __do_page_fault+0x19a/0x430 ? __audit_syscall_entry+0xa8/0x100 SyS_semctl+0x236/0x2c0 ? syscall_trace_leave+0xde/0x130 entry_SYSCALL_64_fastpath+0x12/0x71 Code: 8b 80 88 03 00 00 48 8d 88 60 05 00 00 48 c7 c7 a0 2c a4 81 31 c0 65 8b 15 eb 40 f3 7e e8 08 31 68 00 4d 85 e4 44 8b 4b 08 74 5e <45> 8b 84 24 88 03 00 00 49 8d 8c 24 60 05 00 00 8b 53 04 48 89 RIP [] spin_dump+0x53/0xc0 RSP ---[ end trace 783ebb76612867a0 ]--- NMI watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [test:18053] Modules linked in: 8021q mrp garp stp llc nf_conntrack_ipv4 nf_defrag_ipv4 ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables binfmt_misc ppdev input_leds joydev parport_pc parport floppy serio_raw virtio_balloon virtio_rng virtio_console virtio_net iosf_mbi crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcspkr qxl ttm drm_kms_helper drm snd_hda_codec_generic i2c_piix4 snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer snd soundcore crc32c_intel virtio_pci virtio_ring virtio pata_acpi ata_generic [last unloaded: speedstep_lib] CPU: 3 PID: 18053 Comm: test Tainted: G D 4.2.0-rc5+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014 RIP: native_read_tsc+0x0/0x20 Call Trace: ? delay_tsc+0x40/0x70 __delay+0xf/0x20 do_raw_spin_lock+0x96/0x140 _raw_spin_lock+0xe/0x10 sem_lock_and_putref+0x11/0x70 SYSC_semtimedop+0x7bf/0x960 ? handle_mm_fault+0xbf6/0x1880 ? dequeue_task_fair+0x79/0x4a0 ? __do_page_fault+0x19a/0x430 ? kfree_debugcheck+0x16/0x40 ? __do_page_fault+0x19a/0x430 ? __audit_syscall_entry+0xa8/0x100 ? do_audit_syscall_entry+0x66/0x70 ? syscall_trace_enter_phase1+0x139/0x160 SyS_semtimedop+0xe/0x10 SyS_semop+0x10/0x20 entry_SYSCALL_64_fastpath+0x12/0x71 Code: 47 10 83 e8 01 85 c0 89 47 10 75 08 65 48 89 3d 1f 74 ff 7e c9 c3 0f 1f 44 00 00 55 48 89 e5 e8 87 17 04 00 66 90 c9 c3 0f 1f 00 <55> 48 89 e5 0f 31 89 c1 48 89 d0 48 c1 e0 20 89 c9 48 09 c8 c9 Kernel panic - not syncing: softlockup: hung tasks I wasn't able to trigger any badness on a recent kernel without the proper config debugs enabled, however I have softlockup reports on some kernel versions, in the semaphore code, which are similar as above (the scenario is seen on some servers running IBM DB2 which uses semaphore syscalls). The patch here fixes the race against freeary, by acquiring or waiting on the sem_undo_list lock as necessary (exit_sem can race with freeary, while freeary sets un->semid to -1 and removes the same sem_undo from list_proc or when it removes the last sem_undo). After the patch I'm unable to reproduce the problem using the test case [1]. [1] Test case used below: #include #include #include #include #include #include #include #include #include #define NSEM 1 #define NSET 5 int sid[NSET]; void thread() { struct sembuf op; int s; uid_t pid = getuid(); s = rand() % NSET; op.sem_num = pid % NSEM; op.sem_op = 1; op.sem_flg = SEM_UNDO; semop(sid[s], &op, 1); exit(EXIT_SUCCESS); } void create_set() { int i, j; pid_t p; union { int val; struct semid_ds *buf; unsigned short int *array; struct seminfo *__buf; } un; /* Create and initialize semaphore set */ for (i = 0; i < NSET; i++) { sid[i] = semget(IPC_PRIVATE , NSEM, 0644 | IPC_CREAT); if (sid[i] < 0) { perror("semget"); exit(EXIT_FAILURE); } } un.val = 0; for (i = 0; i < NSET; i++) { for (j = 0; j < NSEM; j++) { if (semctl(sid[i], j, SETVAL, un) < 0) perror("semctl"); } } /* Launch threads that operate on semaphore set */ for (i = 0; i < NSEM * NSET * NSET; i++) { p = fork(); if (p < 0) perror("fork"); if (p == 0) thread(); } /* Free semaphore set */ for (i = 0; i < NSET; i++) { if (semctl(sid[i], NSEM, IPC_RMID)) perror("IPC_RMID"); } /* Wait for forked processes to exit */ while (wait(NULL)) { if (errno == ECHILD) break; }; } int main(int argc, char **argv) { pid_t p; srand(time(NULL)); while (1) { p = fork(); if (p < 0) { perror("fork"); exit(EXIT_FAILURE); } if (p == 0) { create_set(); goto end; } /* Wait for forked processes to exit */ while (wait(NULL)) { if (errno == ECHILD) break; }; } end: return 0; } [akpm@linux-foundation.org: use normal comment layout] Signed-off-by: Herton R. Krzesinski Acked-by: Manfred Spraul Cc: Davidlohr Bueso Cc: Rafael Aquini CC: Aristeu Rozanski Cc: David Jeffery Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [lizf: Backported to 3.4: adjust context] Signed-off-by: Zefan Li

ipc, msg: fix message length check for negative values

2014-04-14T13:44:16Z

commit 4e9b45a19241354daec281d7a785739829b52359 upstream. On 64 bit systems the test for negative message sizes is bogus as the size, which may be positive when evaluated as a long, will get truncated to an int when passed to load_msg(). So a long might very well contain a positive value but when truncated to an int it would become negative. That in combination with a small negative value of msg_ctlmax (which will be promoted to an unsigned type for the comparison against msgsz, making it a big positive value and therefore make it pass the check) will lead to two problems: 1/ The kmalloc() call in alloc_msg() will allocate a too small buffer as the addition of alen is effectively a subtraction. 2/ The copy_from_user() call in load_msg() will first overflow the buffer with userland data and then, when the userland access generates an access violation, the fixup handler copy_user_handle_tail() will try to fill the remainder with zeros -- roughly 4GB. That almost instantly results in a system crash or reset. ,-[ Reproducer (needs to be run as root) ]-- | #include | #include | #include | #include | | int main(void) { | long msg = 1; | int fd; | | fd = open("/proc/sys/kernel/msgmax", O_WRONLY); | write(fd, "-1", 2); | close(fd); | | msgsnd(0, &msg, 0xfffffff0, IPC_NOWAIT); | | return 0; | } '--- Fix the issue by preventing msgsz from getting truncated by consistently using size_t for the message length. This way the size checks in do_msgsnd() could still be passed with a negative value for msg_ctlmax but we would fail on the buffer allocation in that case and error out. Also change the type of m_ts from int to size_t to avoid similar nastiness in other code paths -- it is used in similar constructs, i.e. signed vs. unsigned checks. It should never become negative under normal circumstances, though. Setting msg_ctlmax to a negative value is an odd configuration and should be prevented. As that might break existing userland, it will be handled in a separate commit so it could easily be reverted and reworked without reintroducing the above described bug. Hardening mechanisms for user copy operations would have catched that bug early -- e.g. checking slab object sizes on user copy operations as the usercopy feature of the PaX patch does. Or, for that matter, detect the long vs. int sign change due to truncation, as the size overflow plugin of the very same patch does. [akpm@linux-foundation.org: fix i386 min() warnings] Signed-off-by: Mathias Krause Cc: Pax Team Cc: Davidlohr Bueso Cc: Brad Spengler Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: - Adjust context - Drop changes to alloc_msg() and copy_msg(), which don't exist] Signed-off-by: Ben Hutchings Cc: Qiang Huang Cc: Li Zefan Cc: Jianguo Wu Signed-off-by: Greg Kroah-Hartman

ipc/msg: fix race around refcount

2014-03-31T04:40:31Z

[fixed differently in 6062a8dc0517bce23e3c2f7d2fea5e22411269a3 upstream.] In older kernels (before v3.10) ipc_rcu_hdr->refcount was non-atomic int. There was possuble double-free bug: do_msgsnd() calls ipc_rcu_putref() under msq->q_perm->lock and RCU, while freequeue() calls it while it holds only 'rw_mutex', so there is no sinchronization between them. Two function decrements '2' non-atomically, they both can get '0' as result. do_msgsnd() freequeue() msq = msg_lock_check(ns, msqid); ... ipc_rcu_getref(msq); msg_unlock(msq); schedule(); (caller locks spinlock) expunge_all(msq, -EIDRM); ss_wakeup(&msq->q_senders, 1); msg_rmid(ns, msq); msg_unlock(msq); ipc_lock_by_ptr(&msq->q_perm); ipc_rcu_putref(msq); ipc_rcu_putref(msq); < both may get get --(...)->refcount == 0 > This patch locks ipc_lock and RCU around ipc_rcu_putref in freequeue. ( RCU protects memory for spin_unlock() ) Similar bugs might be in other users of ipc_rcu_putref(). In the mainline this has been fixed in v3.10 indirectly in commmit 6062a8dc0517bce23e3c2f7d2fea5e22411269a3 ("ipc,sem: fine grained locking for semtimedop") by Rik van Riel. That commit optimized locking and converted refcount into atomic. I'm not sure that anybody should care about this bug: it's very-very unlikely and no longer exists in actual mainline. I've found this just by looking into the code, probably this never happens in real life. Signed-off-by: Konstantin Khlebnikov

hugetlbfs: fix mmap failure in unaligned size request

2013-05-19T17:54:48Z

commit af73e4d9506d3b797509f3c030e7dcd554f7d9c4 upstream. The current kernel returns -EINVAL unless a given mmap length is "almost" hugepage aligned. This is because in sys_mmap_pgoff() the given length is passed to vm_mmap_pgoff() as it is without being aligned with hugepage boundary. This is a regression introduced in commit 40716e29243d ("hugetlbfs: fix alignment of huge page requests"), where alignment code is pushed into hugetlb_file_setup() and the variable len in caller side is not changed. To fix this, this patch partially reverts that commit, and adds alignment code in caller side. And it also introduces hstate_sizelog() in order to get proper hstate to specified hugepage size. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=56881 [akpm@linux-foundation.org: fix warning when CONFIG_HUGETLB_PAGE=n] Signed-off-by: Naoya Horiguchi Signed-off-by: Johannes Weiner Reported-by: Cc: Steven Truelove Cc: Jianguo Wu Cc: Hugh Dickins Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Jianguo Wu Signed-off-by: Greg Kroah-Hartman

ipc: sysv shared memory limited to 8TiB

2013-05-08T02:51:56Z

commit d69f3bad4675ac519d41ca2b11e1c00ca115cecd upstream. Trying to run an application which was trying to put data into half of memory using shmget(), we found that having a shmall value below 8EiB-8TiB would prevent us from using anything more than 8TiB. By setting kernel.shmall greater than 8EiB-8TiB would make the job work. In the newseg() function, ns->shm_tot which, at 8TiB is INT_MAX. ipc/shm.c: 458 static int newseg(struct ipc_namespace *ns, struct ipc_params *params) 459 { ... 465 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT; ... 474 if (ns->shm_tot + numpages > ns->shm_ctlall) 475 return -ENOSPC; [akpm@linux-foundation.org: make ipc/shm.c:newseg()'s numpages size_t, not int] Signed-off-by: Robin Holt Reported-by: Alex Thorlton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile

2012-03-29T21:49:45Z

Pull arch/tile (really asm-generic) update from Chris Metcalf: "These are a couple of asm-generic changes that apply to tile." * git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile: compat: use sys_sendfile64() implementation for sendfile syscall [PATCH v3] ipc: provide generic compat versions of IPC syscalls

Merge branch 'akpm' (Andrew's patch-bomb)

2012-03-22T16:04:48Z

Merge first batch of patches from Andrew Morton: "A few misc things and all the MM queue" * emailed from Andrew Morton : (92 commits) memcg: avoid THP split in task migration thp: add HPAGE_PMD_* definitions for !CONFIG_TRANSPARENT_HUGEPAGE memcg: clean up existing move charge code mm/memcontrol.c: remove unnecessary 'break' in mem_cgroup_read() mm/memcontrol.c: remove redundant BUG_ON() in mem_cgroup_usage_unregister_event() mm/memcontrol.c: s/stealed/stolen/ memcg: fix performance of mem_cgroup_begin_update_page_stat() memcg: remove PCG_FILE_MAPPED memcg: use new logic for page stat accounting memcg: remove PCG_MOVE_LOCK flag from page_cgroup memcg: simplify move_account() check memcg: remove EXPORT_SYMBOL(mem_cgroup_update_page_stat) memcg: kill dead prev_priority stubs memcg: remove PCG_CACHE page_cgroup flag memcg: let css_get_next() rely upon rcu_read_lock() cgroup: revert ss_id_lock to spinlock idr: make idr_get_next() good for rcu_read_lock() memcg: remove unnecessary thp check in page stat accounting memcg: remove redundant returns memcg: enum lru_list lru ...

hugetlbfs: fix alignment of huge page requests

2012-03-22T00:54:59Z

When calling shmget() with SHM_HUGETLB, shmget aligns the request size to PAGE_SIZE, but this is not sufficient. Modify hugetlb_file_setup() to align requests to the huge page size, and to accept an address argument so that all alignment checks can be performed in hugetlb_file_setup(), rather than in its callers. Change newseg() and mmap_pgoff() to match the new prototype and eliminate a now redundant alignment check. [akpm@linux-foundation.org: fix build] Signed-off-by: Steven Truelove Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2012-03-21T20:36:41Z

Pull vfs pile 1 from Al Viro: "This is _not_ all; in particular, Miklos' and Jan's stuff is not there yet." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (64 commits) ext4: initialization of ext4_li_mtx needs to be done earlier debugfs-related mode_t whack-a-mole hfsplus: add an ioctl to bless files hfsplus: change finder_info to u32 hfsplus: initialise userflags qnx4: new helper - try_extent() qnx4: get rid of qnx4_bread/qnx4_getblk take removal of PF_FORKNOEXEC to flush_old_exec() trim includes in inode.c um: uml_dup_mmap() relies on ->mmap_sem being held, but activate_mm() doesn't hold it um: embed ->stub_pages[] into mmu_context gadgetfs: list_for_each_safe() misuse ocfs2: fix leaks on failure exits in module_init ecryptfs: make register_filesystem() the last potential failure exit ntfs: forgets to unregister sysctls on register_filesystem() failure logfs: missing cleanup on register_filesystem() failure jfs: mising cleanup on register_filesystem() failure make configfs_pin_fs() return root dentry on success configfs: configfs_create_dir() has parent dentry in dentry->d_parent configfs: sanitize configfs_create() ...