The patch titled
proc: fix pagemap_read() error case
has been removed from the -mm tree. Its filename was
proc-fix-pagemap_read-error-case.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: proc: fix pagemap_read() error case
From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Currently, pagemap_read() has three error and/or corner case handling
mistake.
(1) If ppos parameter is wrong, mm refcount will be leak.
(2) If count parameter is 0, mm refcount will be leak too.
(3) If the current task is sleeping in kmalloc() and the system
is out of memory and oom-killer kill the proc associated task,
mm_refcount prevent the task free its memory. then system may
hang up.
<Quote Hugh's explain why we shold call kmalloc() before get_mm()>
check_mem_permission gets a reference to the mm. If we
__get_free_page after check_mem_permission, imagine what happens if the
system is out of memory, and the mm we're looking at is selected for
killing by the OOM killer: while we wait in __get_free_page for more
memory, no memory is freed from the selected mm because it cannot reach
exit_mmap while we hold that reference.
This patch fixes the above three.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jovi Zhang <bookjovi@xxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Stephen Wilson <wilsons@xxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff -puN fs/proc/task_mmu.c~proc-fix-pagemap_read-error-case fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~proc-fix-pagemap_read-error-case
+++ a/fs/proc/task_mmu.c
@@ -771,18 +771,12 @@ static ssize_t pagemap_read(struct file
if (!task)
goto out;
- mm = mm_for_maps(task);
- ret = PTR_ERR(mm);
- if (!mm || IS_ERR(mm))
- goto out_task;
-
ret = -EINVAL;
/* file position must be aligned */
if ((*ppos % PM_ENTRY_BYTES) || (count % PM_ENTRY_BYTES))
goto out_task;
ret = 0;
-
if (!count)
goto out_task;
@@ -790,7 +784,12 @@ static ssize_t pagemap_read(struct file
pm.buffer = kmalloc(pm.len, GFP_TEMPORARY);
ret = -ENOMEM;
if (!pm.buffer)
- goto out_mm;
+ goto out_task;
+
+ mm = mm_for_maps(task);
+ ret = PTR_ERR(mm);
+ if (!mm || IS_ERR(mm))
+ goto out_free;
pagemap_walk.pmd_entry = pagemap_pte_range;
pagemap_walk.pte_hole = pagemap_pte_hole;
@@ -833,7 +832,7 @@ static ssize_t pagemap_read(struct file
len = min(count, PM_ENTRY_BYTES * pm.pos);
if (copy_to_user(buf, pm.buffer, len)) {
ret = -EFAULT;
- goto out_free;
+ goto out_mm;
}
copied += len;
buf += len;
@@ -843,10 +842,10 @@ static ssize_t pagemap_read(struct file
if (!ret || ret == PM_END_OF_BUFFER)
ret = copied;
-out_free:
- kfree(pm.buffer);
out_mm:
mmput(mm);
+out_free:
+ kfree(pm.buffer);
out_task:
put_task_struct(task);
out:
_
Patches currently in -mm which might be from kosaki.motohiro@xxxxxxxxxxxxxx are
origin.patch
mm-increase-reclaim_distance-to-30.patch
slab-use-numa_no_node.patch
vmscanmemcg-memcg-aware-swap-token.patch
vmscan-implement-swap-token-trace.patch
vmscan-implement-swap-token-priority-aging.patch
cpusets-randomize-node-rotor-used-in-cpuset_mem_spread_node.patch
cpusets-randomize-node-rotor-used-in-cpuset_mem_spread_node-cpusets-initialize-spread-rotor-lazily.patch
cpumask-convert-for_each_cpumask-with-for_each_cpu.patch
cpumask-convert-cpumask_of_cpu-to-cpumask_of.patch
cpumask-alloc_cpumask_var-use-numa_no_node.patch
cpumask-add-cpumask_var_t-documentation.patch
kexec-remove-kmsg_dump_kexec.patch
kexec-remove-kmsg_dump_kexec-fix.patch
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