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 [<ffffffff810d6053>] spin_dump+0x53/0xc0
RSP <ffff88003750fd68>
---[ 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 <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
#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 <herton@redhat.com>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Rafael Aquini <aquini@redhat.com>
CC: Aristeu Rozanski <aris@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
(cherry picked from commit a1c4fb80c5d94ef61a77c1e891cae616a50d8d3c)
Signed-off-by: Willy Tarreau <w@1wt.eu>
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 <dvyukov@google.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 2.6.32: - Adjust context - The error path being moved looks a little different] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Willy Tarreau <w@1wt.eu>
commit e8577d1f0329d4842e8302e289fb2c22156abef4 upstream. ipc_addid() makes a new ipc identifier visible to everyone. New objects start as locked, so that the caller can complete the initialization after the call. Within struct sem_array, at least sma->sem_base and sma->sem_nsems are accessed without any locks, therefore this approach doesn't work. Thus: Move the ipc_addid() to the end of the initialization. Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Reported-by: Rik van Riel <riel@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 2.6.32: - Adjust context - The error path being moved looks a little different] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Willy Tarreau <w@1wt.eu>
commit 982f7c2b2e6a28f8f266e075d92e19c0dd4c6e56 upstream. The semctl syscall has several code paths that lead to the leakage of uninitialized kernel stack memory (namely the IPC_INFO, SEM_INFO, IPC_STAT, and SEM_STAT commands) during the use of the older, obsolete version of the semid_ds struct. The copy_semid_to_user() function declares a semid_ds struct on the stack and copies it back to the user without initializing or zeroing the "sem_base", "sem_pending", "sem_pending_last", and "undo" pointers, allowing the leakage of 16 bytes of kernel stack memory. The code is still reachable on 32-bit systems - when calling semctl() newer glibc's automatically OR the IPC command with the IPC_64 flag, but invoking the syscall directly allows users to use the older versions of the struct. Signed-off-by: Dan Rosenberg <dan.j.rosenberg@gmail.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
commit 3af54c9bd9e6f14f896aac1bb0e8405ae0bc7a44 upstream.
The shmid_ds structure is copied to userland with shm_unused{,2,3}
fields unitialized. It leads to leaking of contents of kernel stack
memory.
Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
commit 03145beb455cf5c20a761e8451e30b8a74ba58d9 upstream. This takes care of leaking uninitialized kernel stack memory to userspace from non-zeroed fields in structs in compat ipc functions. Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
commit 4294a8eedb17bbc45e1e7447c2a4d05332943248 upstream. We leak fd on lookup_one_len() failure Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
commit 7d6feeb287c61aafa88f06345387b1188edf4b86 upstream. We have apparently had a memory leak since 7ca7e564e049d8b350ec9d958ff25eaa24226352 "ipc: store ipcs into IDRs" in 2007. The idr of which 3 exist for each ipc namespace is never freed. This patch simply frees them when the ipcns is freed. I don't believe any idr_remove() are done from rcu (and could therefore be delayed until after this idr_destroy()), so the patch should be safe. Some quick testing showed no harm, and the memory leak fixed. Caught by kmemleak. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This backports the following upstream commits all as one patch: 54f5de709984bae0d31d823ff03de755f9dcac54 ecc1a8993751de4e82eb18640d631dae1f626bd6 1a0ef85f84feb13f07b604fcf5b90ef7c2b5c82f f106af4e90eadd76cfc0b5325f659619e08fb762 097eed103862f9c6a97f2e415e21d1134017b135 935874141df839c706cd6cdc438e85eb69d1525e 0ec62d290912bb4b989be7563851bc364ec73b56 c4caa778157dbbf04116f0ac2111e389b5cd7a29 2ea1d13f64efdf49319e86c87d9ba38c30902782 570dcf2c15463842e384eb597a87c1e39bead99b 564b3bffc619dcbdd160de597b0547a7017ea010 0067bd8a55862ac9dd212bd1c4f6f5bff1ca1301 f8b7256096a20436f6d0926747e3ac3d64c81d24 8c7b49b3ecd48923eb64ff57e07a1cdb74782970 9206de95b1ea68357996ec02be5db0638a0de2c1 2c6a10161d0b5fc047b5bd81b03693b9af99fab5 05d72faa6d13c9d857478a5d35c85db9adada685 bb52d6694002b9d632bb355f64daa045c6293a4e e77414e0aad6a1b063ba5e5750c582c75327ea6a aa65607373a4daf2010e8c3867b6317619f3c1a3 Backport done by Greg Kroah-Hartman. Only minor tweaks were needed. Cc: David S. Miller <davem@davemloft.net> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* mark struct vm_area_struct::vm_ops as const * mark vm_ops in AGP code But leave TTM code alone, something is fishy there with global vm_ops being used. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>