The patch titled
ksm: limit the num of mem regions user can register per fd
has been added to the -mm tree. Its filename is
ksm-add-ksm-kernel-shared-memory-driver-limiting-the-num-of-mem-regions-user-can-register-per-fd.patch
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See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: ksm: limit the num of mem regions user can register per fd
From: Izik Eidus <ieidus@xxxxxxxxxx>
Right now user can open /dev/ksm fd and register unlimited number of
regions, such behavior may allocate unlimited amount of kernel memory
and get the whole host into out of memory situation.
Signed-off-by: Izik Eidus <ieidus@xxxxxxxxxx>
Cc: Chris Wright <chrisw@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Avi Kivity <avi@xxxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff -puN mm/ksm.c~ksm-add-ksm-kernel-shared-memory-driver-limiting-the-num-of-mem-regions-user-can-register-per-fd mm/ksm.c
--- a/mm/ksm.c~ksm-add-ksm-kernel-shared-memory-driver-limiting-the-num-of-mem-regions-user-can-register-per-fd
+++ a/mm/ksm.c
@@ -48,6 +48,9 @@ static int rmap_hash_size;
module_param(rmap_hash_size, int, 0);
MODULE_PARM_DESC(rmap_hash_size, "Hash table size for the reverse mapping");
+static int regions_per_fd;
+module_param(regions_per_fd, int, 0);
+
/*
* ksm_mem_slot - hold information for an userspace scanning range
* (the scanning for this region will be from addr untill addr +
@@ -67,6 +70,7 @@ struct ksm_mem_slot {
*/
struct ksm_sma {
struct list_head sma_slots;
+ int nregions;
};
/**
@@ -452,6 +456,11 @@ static int ksm_sma_ioctl_register_memory
struct ksm_mem_slot *slot;
int ret = -EPERM;
+ if ((ksm_sma->nregions + 1) > regions_per_fd) {
+ ret = -EBUSY;
+ goto out;
+ }
+
slot = kzalloc(sizeof(struct ksm_mem_slot), GFP_KERNEL);
if (!slot) {
ret = -ENOMEM;
@@ -472,6 +481,7 @@ static int ksm_sma_ioctl_register_memory
list_add_tail(&slot->link, &slots);
list_add_tail(&slot->sma_link, &ksm_sma->sma_slots);
+ ksm_sma->nregions++;
up_write(&slots_lock);
return 0;
@@ -510,6 +520,7 @@ static int ksm_sma_ioctl_remove_memory_r
mmput(slot->mm);
list_del(&slot->sma_link);
kfree(slot);
+ ksm_sma->nregions--;
}
up_write(&slots_lock);
return 0;
@@ -1387,6 +1398,7 @@ static int ksm_dev_ioctl_create_shared_m
}
INIT_LIST_HEAD(&ksm_sma->sma_slots);
+ ksm_sma->nregions = 0;
fd = anon_inode_getfd("ksm-sma", &ksm_sma_fops, ksm_sma, 0);
if (fd < 0)
@@ -1629,6 +1641,9 @@ static int __init ksm_init(void)
if (r)
goto out_free1;
+ if (!regions_per_fd)
+ regions_per_fd = 1024;
+
ksm_thread = kthread_run(ksm_scan_thread, NULL, "kksmd");
if (IS_ERR(ksm_thread)) {
printk(KERN_ERR "ksm: creating kthread failed\n");
_
Patches currently in -mm which might be from ieidus@xxxxxxxxxx are
linux-next.patch
ksm-mmu_notifiers-add-set_pte_at_notify.patch
ksm-add-get_pte-helper-function-fetching-pte-for-va.patch
ksm-add-get_pte-helper-function-fetching-pte-for-va-fix.patch
ksm-add-page_wrprotect-write-protecting-page.patch
ksm-add-replace_page-change-the-page-pte-is-pointing-to.patch
ksm-add-ksm-kernel-shared-memory-driver.patch
ksm-add-ksm-kernel-shared-memory-driver-checkpatch-fixes.patch
ksm-add-ksm-kernel-shared-memory-driver-fix-unsafe-pte-fetching.patch
ksm-add-ksm-kernel-shared-memory-driver-fix.patch
ksm-add-ksm-kernel-shared-memory-driver-limiting-the-num-of-mem-regions-user-can-register-per-fd.patch
ksm-add-ksm-kernel-shared-memory-driver-dont-allow-overlap-memory-addresses-registrations.patch
ksm-add-ksm-kernel-shared-memory-driver-change-the-ksm_remove_memory_region-ioctl.patch
ksm-add-ksm-kernel-shared-memory-driver-change-the-prot-handling-to-use-the-generic-helper-functions.patch
ksm-add-ksm-kernel-shared-memory-driver-use-another-miscdevice-minor-number.patch
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