From: Andrew Morton <akpm@linux-foundation.org>
To: ak@linux.intel.com, akpm@linux-foundation.org,
linux-mm@kvack.org, mike.kravetz@oracle.com,
mm-commits@vger.kernel.org, songmuchun@bytedance.com,
torvalds@linux-foundation.org
Subject: [patch 17/19] mm/hugetlb: fix a race between hugetlb sysctl handlers
Date: Fri, 04 Sep 2020 16:36:13 -0700 [thread overview]
Message-ID: <20200904233613.MaCSNiMVj%akpm@linux-foundation.org> (raw)
In-Reply-To: <20200904163454.4db0e6ce0c4584d2653678a3@linux-foundation.org>
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm/hugetlb: fix a race between hugetlb sysctl handlers
There is a race between the assignment of `table->data` and write value to
the pointer of `table->data` in the __do_proc_doulongvec_minmax() on the
other thread.
CPU0: CPU1:
proc_sys_write
hugetlb_sysctl_handler proc_sys_call_handler
hugetlb_sysctl_handler_common hugetlb_sysctl_handler
table->data = &tmp; hugetlb_sysctl_handler_common
table->data = &tmp;
proc_doulongvec_minmax
do_proc_doulongvec_minmax sysctl_head_finish
__do_proc_doulongvec_minmax unuse_table
i = table->data;
*i = val; // corrupt CPU1's stack
Fix this by duplicating the `table`, and only update the duplicate of
it. And introduce a helper of proc_hugetlb_doulongvec_minmax() to
simplify the code.
The following oops was seen:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
Code: Bad RIP value.
...
Call Trace:
? set_max_huge_pages+0x3da/0x4f0
? alloc_pool_huge_page+0x150/0x150
? proc_doulongvec_minmax+0x46/0x60
? hugetlb_sysctl_handler_common+0x1c7/0x200
? nr_hugepages_store+0x20/0x20
? copy_fd_bitmaps+0x170/0x170
? hugetlb_sysctl_handler+0x1e/0x20
? proc_sys_call_handler+0x2f1/0x300
? unregister_sysctl_table+0xb0/0xb0
? __fd_install+0x78/0x100
? proc_sys_write+0x14/0x20
? __vfs_write+0x4d/0x90
? vfs_write+0xef/0x240
? ksys_write+0xc0/0x160
? __ia32_sys_read+0x50/0x50
? __close_fd+0x129/0x150
? __x64_sys_write+0x43/0x50
? do_syscall_64+0x6c/0x200
? entry_SYSCALL_64_after_hwframe+0x44/0xa9
Link: http://lkml.kernel.org/r/20200828031146.43035-1-songmuchun@bytedance.com
Fixes: e5ff215941d5 ("hugetlb: multiple hstates for multiple page sizes")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/hugetlb.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
--- a/mm/hugetlb.c~mm-hugetlb-fix-a-race-between-hugetlb-sysctl-handlers
+++ a/mm/hugetlb.c
@@ -3465,6 +3465,22 @@ static unsigned int allowed_mems_nr(stru
}
#ifdef CONFIG_SYSCTL
+static int proc_hugetlb_doulongvec_minmax(struct ctl_table *table, int write,
+ void *buffer, size_t *length,
+ loff_t *ppos, unsigned long *out)
+{
+ struct ctl_table dup_table;
+
+ /*
+ * In order to avoid races with __do_proc_doulongvec_minmax(), we
+ * can duplicate the @table and alter the duplicate of it.
+ */
+ dup_table = *table;
+ dup_table.data = out;
+
+ return proc_doulongvec_minmax(&dup_table, write, buffer, length, ppos);
+}
+
static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
@@ -3476,9 +3492,8 @@ static int hugetlb_sysctl_handler_common
if (!hugepages_supported())
return -EOPNOTSUPP;
- table->data = &tmp;
- table->maxlen = sizeof(unsigned long);
- ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
+ ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos,
+ &tmp);
if (ret)
goto out;
@@ -3521,9 +3536,8 @@ int hugetlb_overcommit_handler(struct ct
if (write && hstate_is_gigantic(h))
return -EINVAL;
- table->data = &tmp;
- table->maxlen = sizeof(unsigned long);
- ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
+ ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos,
+ &tmp);
if (ret)
goto out;
_
next prev parent reply other threads:[~2020-09-04 23:36 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 23:34 incoming Andrew Morton
2020-09-04 23:35 ` [patch 01/19] memcg: fix use-after-free in uncharge_batch Andrew Morton
2020-09-04 23:35 ` [patch 02/19] mm: memcg: fix memcg reclaim soft lockup Andrew Morton
2020-09-04 23:35 ` [patch 03/19] mm: slub: fix conversion of freelist_corrupted() Andrew Morton
2020-09-04 23:35 ` [patch 04/19] MAINTAINERS: update Cavium/Marvell entries Andrew Morton
2020-09-04 23:35 ` [patch 05/19] MAINTAINERS: add LLVM maintainers Andrew Morton
2020-09-04 23:35 ` [patch 06/19] MAINTAINERS: IA64: mark Status as Odd Fixes only Andrew Morton
2020-09-04 23:35 ` [patch 07/19] mm: track page table modifications in __apply_to_page_range() Andrew Morton
2020-09-04 23:35 ` [patch 08/19] ipc: adjust proc_ipc_sem_dointvec definition to match prototype Andrew Morton
2020-09-04 23:35 ` [patch 09/19] fork: adjust sysctl_max_threads " Andrew Morton
2020-09-04 23:35 ` [patch 10/19] checkpatch: fix the usage of capture group ( ... ) Andrew Morton
2020-09-04 23:35 ` [patch 11/19] mm: madvise: fix vma user-after-free Andrew Morton
2020-09-04 23:35 ` [patch 12/19] mm/migrate: fixup setting UFFD_WP flag Andrew Morton
2020-09-04 23:36 ` [patch 13/19] mm/rmap: fixup copying of soft dirty and uffd ptes Andrew Morton
2020-09-04 23:36 ` [patch 14/19] mm/migrate: remove unnecessary is_zone_device_page() check Andrew Morton
2020-09-04 23:36 ` [patch 15/19] mm/migrate: preserve soft dirty in remove_migration_pte() Andrew Morton
2020-09-04 23:36 ` [patch 16/19] mm/hugetlb: try preferred node first when alloc gigantic page from cma Andrew Morton
2020-09-04 23:36 ` Andrew Morton [this message]
2020-09-04 23:36 ` [patch 18/19] mm/khugepaged.c: fix khugepaged's request size in collapse_file Andrew Morton
2020-09-04 23:36 ` [patch 19/19] include/linux/log2.h: add missing () around n in roundup_pow_of_two() Andrew Morton
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