Subject: + futex-switch-to-user_ds-for-futex-test.patch added to -mm tree
To: geert@xxxxxxxxxxxxxx,dvhart@xxxxxxxxxxxxxxx,fthain@xxxxxxxxxxxxxxxxxxx,patrickjmc@xxxxxxxxx,rusty@xxxxxxxxxxxxxxx,schwab@xxxxxxxxxxxxxx,stable@xxxxxxxxxxxxxxx,tglx@xxxxxxxxxxxxx,tuxist@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 11 Dec 2013 15:10:07 -0800
The patch titled
Subject: futex: switch to USER_DS for futex test
has been added to the -mm tree. Its filename is
futex-switch-to-user_ds-for-futex-test.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/futex-switch-to-user_ds-for-futex-test.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/futex-switch-to-user_ds-for-futex-test.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Subject: futex: switch to USER_DS for futex test
Since e4f2dfbb5e92b ("m68k: implement futex.h to support userspace robust
futexes and PI mutexes"), the kernel crashes during boot up on MC68030:
Data read fault at 0x00000000 in Super Data (pc=0x3afec)
BAD KERNEL BUSERR
Oops: 00000000
Modules linked in:
PC: [<0003afec>] cmpxchg_futex_value_locked+0x14/0x4a
SR: 2004 SP: 0082fed4 a2: 0082c000
d0: 00000000 d1: 00000001 d2: 00000018 d3: 00000000
d4: 00000061 d5: 00001000 a0: 00000000 a1: 0082e000
Process swapper (pid: 1, task=0082c000)
Frame format=B ssw=074d isc=4a80 isb=661c daddr=00000000 dobuf=00000001
baddr=0003aff2 dibuf=00000000 ver=f
Stack from 0082ff5c:
002b8cb8 0082ff70 00000000 00000000 00000000 00000000 00000000 000020ac
00000018 00000007 00000061 00001000 00000000 00000000 002cab50 00002008
002b3a56 002b8ca4 0082c3f0 00000000 0082c53c 001e316a 00000000 00000000
001e3172 001e316a 000025d4 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 20000000
00000000
Call Trace: [<002b8cb8>] futex_init+0x14/0x54
[<000020ac>] do_one_initcall+0xa4/0x144
[<00001000>] kernel_pg_dir+0x0/0x1000
[<00002008>] do_one_initcall+0x0/0x144
[<002b3a56>] kernel_init_freeable+0xca/0x152
[<002b8ca4>] futex_init+0x0/0x54
[<001e316a>] kernel_init+0x0/0xc8
[<001e3172>] kernel_init+0x8/0xc8
[<001e316a>] kernel_init+0x0/0xc8
[<000025d4>] ret_from_kernel_thread+0xc/0x14
This happens because the futex test in futex_init() lacks a switch to the
USER_DS address space, while cmpxchg_futex_value_locked() and
futex_atomic_cmpxchg_inatomic() operate on userspace pointers (albeit NULL
for this particular test).
Fix this by switching to USER_DS before running the test, and restoring
the old address space afterwards.
Reported-by: Tuxist <tuxist@xxxxxxxxx>
Reported-by: Patrick McCarthy <patrickjmc@xxxxxxxxx>
Bisected-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
Suggested-by: Andreas Schwab <schwab@xxxxxxxxxxxxxx>
Tested-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Darren Hart <dvhart@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/futex.c | 5 +++++
1 file changed, 5 insertions(+)
diff -puN kernel/futex.c~futex-switch-to-user_ds-for-futex-test kernel/futex.c
--- a/kernel/futex.c~futex-switch-to-user_ds-for-futex-test
+++ a/kernel/futex.c
@@ -63,6 +63,7 @@
#include <linux/sched/rt.h>
#include <linux/hugetlb.h>
#include <linux/freezer.h>
+#include <linux/uaccess.h>
#include <asm/futex.h>
@@ -2732,6 +2733,7 @@ SYSCALL_DEFINE6(futex, u32 __user *, uad
static int __init futex_init(void)
{
+ mm_segment_t fs;
u32 curval;
int i;
@@ -2745,8 +2747,11 @@ static int __init futex_init(void)
* implementation, the non-functional ones will return
* -ENOSYS.
*/
+ fs = get_fs();
+ set_fs(USER_DS);
if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT)
futex_cmpxchg_enabled = 1;
+ set_fs(fs);
for (i = 0; i < ARRAY_SIZE(futex_queues); i++) {
plist_head_init(&futex_queues[i].chain);
_
Patches currently in -mm which might be from geert@xxxxxxxxxxxxxx are
origin.patch
drivers-rtc-rtc-s5mc-fix-info-rtc-assignment.patch
rtc-s5m-fix-unsuccesful-irq-request-during-probe.patch
rtc-s5m-limit-endless-loop-waiting-for-register-update.patch
rtc-s5m-enable-irq-wake-during-suspend.patch
mfd-rtc-s5m-fix-register-updating-by-adding-regmap-for-rtc.patch
inith-add-missing-initcall-variants.patch
futex-switch-to-user_ds-for-futex-test.patch
drivers-gpu-drm-drm_edid_loadc-make-edid_load-return-a-void.patch
asm-typesh-remove-include-asm-generic-int-l64h.patch
maintainers-add-an-entry-for-the-macintosh-hfsplus-filesystem.patch
init-mainc-remove-unused-declaration-of-tc_init.patch
proc-cleanup-simplify-get_task_state-task_state_array.patch
linux-next.patch
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