* NULL-ptr deref in mmput via sys_migrate_pages in 3.4-rc4 (proly missing mm==NULL check)
@ 2012-04-23 22:44 Robert Święcki
2012-04-24 14:23 ` Robert Święcki
0 siblings, 1 reply; 4+ messages in thread
From: Robert Święcki @ 2012-04-23 22:44 UTC (permalink / raw)
To: linux-kernel
mm/mempolicy.c
1362 mm = get_task_mm(task);
1363 put_task_struct(task);
1364 if (mm)
1365 err = do_migrate_pages(mm, old, new,
1366 capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL
: MPOL_MF_MOVE);
1367 else
1368 err = -EINVAL;
1369
1370 mmput(mm);
Where mmput doesn't check for mm
kernel/fork.c
567 void mmput(struct mm_struct *mm)
568 {
569 might_sleep();
570
571 if (atomic_dec_and_test(&mm->mm_users)) {
causes NULL-ptr deref
(gdb) target remote /dev/ttyS0
Remote debugging using /dev/ttyS0
mmput (mm=0x0) at kernel/fork.c:571
571 if (atomic_dec_and_test(&mm->mm_users)) {
(gdb) bt
#0 mmput (mm=0x0) at kernel/fork.c:571
#1 0xffffffff8116a1e0 in sys_migrate_pages (pid=<optimized out>,
maxnode=<optimized out>, old_nodes=<optimized out>,
new_nodes=<optimized out>) at mm/mempolicy.c:1370
#2 0xffffffff820726c9 in ?? () at arch/x86/ia32/ia32entry.S:425
(gdb) up
#1 0xffffffff8116a1e0 in sys_migrate_pages (pid=<optimized out>,
maxnode=<optimized out>, old_nodes=<optimized out>,
new_nodes=<optimized out>) at mm/mempolicy.c:1370
1370 mmput(mm);
(gdb) p mm
$1 = (struct mm_struct *) 0x0
(gdb) p task->mm
$2 = (struct mm_struct *) 0x0
--
Robert Święcki
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: NULL-ptr deref in mmput via sys_migrate_pages in 3.4-rc4 (proly missing mm==NULL check)
2012-04-23 22:44 NULL-ptr deref in mmput via sys_migrate_pages in 3.4-rc4 (proly missing mm==NULL check) Robert Święcki
@ 2012-04-24 14:23 ` Robert Święcki
2012-04-25 20:15 ` Dave Jones
0 siblings, 1 reply; 4+ messages in thread
From: Robert Święcki @ 2012-04-24 14:23 UTC (permalink / raw)
To: linux-kernel; +Cc: Christoph Lameter
On Tue, Apr 24, 2012 at 12:44 AM, Robert Święcki <robert@swiecki.net> wrote:
> mm/mempolicy.c
> 1362 mm = get_task_mm(task);
> 1363 put_task_struct(task);
> 1364 if (mm)
> 1365 err = do_migrate_pages(mm, old, new,
> 1366 capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL
> : MPOL_MF_MOVE);
> 1367 else
> 1368 err = -EINVAL;
> 1369
> 1370 mmput(mm);
>
> Where mmput doesn't check for mm
>
> kernel/fork.c
> 567 void mmput(struct mm_struct *mm)
> 568 {
> 569 might_sleep();
> 570
> 571 if (atomic_dec_and_test(&mm->mm_users)) {
>
>
> causes NULL-ptr deref
>
> (gdb) target remote /dev/ttyS0
> Remote debugging using /dev/ttyS0
> mmput (mm=0x0) at kernel/fork.c:571
> 571 if (atomic_dec_and_test(&mm->mm_users)) {
>
> (gdb) bt
> #0 mmput (mm=0x0) at kernel/fork.c:571
> #1 0xffffffff8116a1e0 in sys_migrate_pages (pid=<optimized out>,
> maxnode=<optimized out>, old_nodes=<optimized out>,
> new_nodes=<optimized out>) at mm/mempolicy.c:1370
> #2 0xffffffff820726c9 in ?? () at arch/x86/ia32/ia32entry.S:425
>
>
> (gdb) up
> #1 0xffffffff8116a1e0 in sys_migrate_pages (pid=<optimized out>,
> maxnode=<optimized out>, old_nodes=<optimized out>,
> new_nodes=<optimized out>) at mm/mempolicy.c:1370
> 1370 mmput(mm);
> (gdb) p mm
> $1 = (struct mm_struct *) 0x0
> (gdb) p task->mm
> $2 = (struct mm_struct *) 0x0
Most likely caused by this patch:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=3268c63eded4612a3d07b56d1e02ce7731e6608e
--
Robert Święcki
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: NULL-ptr deref in mmput via sys_migrate_pages in 3.4-rc4 (proly missing mm==NULL check)
2012-04-24 14:23 ` Robert Święcki
@ 2012-04-25 20:15 ` Dave Jones
0 siblings, 0 replies; 4+ messages in thread
From: Dave Jones @ 2012-04-25 20:15 UTC (permalink / raw)
To: Robert Święcki; +Cc: linux-kernel, Christoph Lameter, linux-mm
Commit 3268c63eded4612a3d07b56d1e02ce7731e6608e introduced two potential NULL dereferences.
Move the mmput calls into the if arms that have already tested for a valid mm.
Reported-by: Robert Święcki <robert@swiecki.net>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Dave Jones <davej@redhat.com>
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index cfb6c86..6de4850 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1361,13 +1361,12 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
mm = get_task_mm(task);
put_task_struct(task);
- if (mm)
+ if (mm) {
err = do_migrate_pages(mm, old, new,
capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
- else
+ mmput(mm);
+ } else
err = -EINVAL;
-
- mmput(mm);
out:
NODEMASK_SCRATCH_FREE(scratch);
diff --git a/mm/migrate.c b/mm/migrate.c
index 51c08a0..d73d860 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1389,15 +1389,15 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
put_task_struct(task);
if (mm) {
- if (nodes)
+ if (nodes) {
err = do_pages_move(mm, task_nodes, nr_pages, pages,
nodes, status, flags);
- else
+ mmput(mm);
+ } else
err = do_pages_stat(mm, nr_pages, pages, status);
} else
err = -EINVAL;
- mmput(mm);
return err;
out:
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: NULL-ptr deref in mmput via sys_migrate_pages in 3.4-rc4 (proly missing mm==NULL check)
@ 2012-04-25 20:15 ` Dave Jones
0 siblings, 0 replies; 4+ messages in thread
From: Dave Jones @ 2012-04-25 20:15 UTC (permalink / raw)
To: Robert Święcki; +Cc: linux-kernel, Christoph Lameter, linux-mm
Commit 3268c63eded4612a3d07b56d1e02ce7731e6608e introduced two potential NULL dereferences.
Move the mmput calls into the if arms that have already tested for a valid mm.
Reported-by: Robert A?wiA?cki <robert@swiecki.net>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Dave Jones <davej@redhat.com>
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index cfb6c86..6de4850 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1361,13 +1361,12 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
mm = get_task_mm(task);
put_task_struct(task);
- if (mm)
+ if (mm) {
err = do_migrate_pages(mm, old, new,
capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
- else
+ mmput(mm);
+ } else
err = -EINVAL;
-
- mmput(mm);
out:
NODEMASK_SCRATCH_FREE(scratch);
diff --git a/mm/migrate.c b/mm/migrate.c
index 51c08a0..d73d860 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1389,15 +1389,15 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
put_task_struct(task);
if (mm) {
- if (nodes)
+ if (nodes) {
err = do_pages_move(mm, task_nodes, nr_pages, pages,
nodes, status, flags);
- else
+ mmput(mm);
+ } else
err = do_pages_stat(mm, nr_pages, pages, status);
} else
err = -EINVAL;
- mmput(mm);
return err;
out:
--
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^ permalink raw reply related [flat|nested] 4+ messages in thread
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2012-04-23 22:44 NULL-ptr deref in mmput via sys_migrate_pages in 3.4-rc4 (proly missing mm==NULL check) Robert Święcki
2012-04-24 14:23 ` Robert Święcki
2012-04-25 20:15 ` Dave Jones
2012-04-25 20:15 ` Dave Jones
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