Revision 85bd839983778fcd0c1c043327b14a046e979b39 authored by Gu Zheng on 10 June 2015, 18:14:43 UTC, committed by Linus Torvalds on 10 June 2015, 23:43:43 UTC
Izumi found the following oops when hot re-adding a node: BUG: unable to handle kernel paging request at ffffc90008963690 IP: __wake_up_bit+0x20/0x70 Oops: 0000 [#1] SMP CPU: 68 PID: 1237 Comm: rs:main Q:Reg Not tainted 4.1.0-rc5 #80 Hardware name: FUJITSU PRIMEQUEST2800E/SB, BIOS PRIMEQUEST 2000 Series BIOS Version 1.87 04/28/2015 task: ffff880838df8000 ti: ffff880017b94000 task.ti: ffff880017b94000 RIP: 0010:[<ffffffff810dff80>] [<ffffffff810dff80>] __wake_up_bit+0x20/0x70 RSP: 0018:ffff880017b97be8 EFLAGS: 00010246 RAX: ffffc90008963690 RBX: 00000000003c0000 RCX: 000000000000a4c9 RDX: 0000000000000000 RSI: ffffea101bffd500 RDI: ffffc90008963648 RBP: ffff880017b97c08 R08: 0000000002000020 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8a0797c73800 R13: ffffea101bffd500 R14: 0000000000000001 R15: 00000000003c0000 FS: 00007fcc7ffff700(0000) GS:ffff880874800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffc90008963690 CR3: 0000000836761000 CR4: 00000000001407e0 Call Trace: unlock_page+0x6d/0x70 generic_write_end+0x53/0xb0 xfs_vm_write_end+0x29/0x80 [xfs] generic_perform_write+0x10a/0x1e0 xfs_file_buffered_aio_write+0x14d/0x3e0 [xfs] xfs_file_write_iter+0x79/0x120 [xfs] __vfs_write+0xd4/0x110 vfs_write+0xac/0x1c0 SyS_write+0x58/0xd0 system_call_fastpath+0x12/0x76 Code: 5d c3 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 48 83 ec 20 65 48 8b 04 25 28 00 00 00 48 89 45 f8 31 c0 48 8d 47 48 <48> 39 47 48 48 c7 45 e8 00 00 00 00 48 c7 45 f0 00 00 00 00 48 RIP [<ffffffff810dff80>] __wake_up_bit+0x20/0x70 RSP <ffff880017b97be8> CR2: ffffc90008963690 Reproduce method (re-add a node):: Hot-add nodeA --> remove nodeA --> hot-add nodeA (panic) This seems an use-after-free problem, and the root cause is zone->wait_table was not set to *NULL* after free it in try_offline_node. When hot re-add a node, we will reuse the pgdat of it, so does the zone struct, and when add pages to the target zone, it will init the zone first (including the wait_table) if the zone is not initialized. The judgement of zone initialized is based on zone->wait_table: static inline bool zone_is_initialized(struct zone *zone) { return !!zone->wait_table; } so if we do not set the zone->wait_table to *NULL* after free it, the memory hotplug routine will skip the init of new zone when hot re-add the node, and the wait_table still points to the freed memory, then we will access the invalid address when trying to wake up the waiting people after the i/o operation with the page is done, such as mentioned above. Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Reported-by: Taku Izumi <izumi.taku@jp.fujitsu.com> Reviewed by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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md5.c
/*
* Cryptographic API.
*
* MD5 Message Digest Algorithm (RFC1321).
*
* Derived from cryptoapi implementation, originally based on the
* public domain implementation written by Colin Plumb in 1993.
*
* Copyright (c) Cryptoapi developers.
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <crypto/internal/hash.h>
#include <crypto/md5.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/cryptohash.h>
#include <asm/byteorder.h>
/* XXX: this stuff can be optimized */
static inline void le32_to_cpu_array(u32 *buf, unsigned int words)
{
while (words--) {
__le32_to_cpus(buf);
buf++;
}
}
static inline void cpu_to_le32_array(u32 *buf, unsigned int words)
{
while (words--) {
__cpu_to_le32s(buf);
buf++;
}
}
static inline void md5_transform_helper(struct md5_state *ctx)
{
le32_to_cpu_array(ctx->block, sizeof(ctx->block) / sizeof(u32));
md5_transform(ctx->hash, ctx->block);
}
static int md5_init(struct shash_desc *desc)
{
struct md5_state *mctx = shash_desc_ctx(desc);
mctx->hash[0] = 0x67452301;
mctx->hash[1] = 0xefcdab89;
mctx->hash[2] = 0x98badcfe;
mctx->hash[3] = 0x10325476;
mctx->byte_count = 0;
return 0;
}
static int md5_update(struct shash_desc *desc, const u8 *data, unsigned int len)
{
struct md5_state *mctx = shash_desc_ctx(desc);
const u32 avail = sizeof(mctx->block) - (mctx->byte_count & 0x3f);
mctx->byte_count += len;
if (avail > len) {
memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
data, len);
return 0;
}
memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
data, avail);
md5_transform_helper(mctx);
data += avail;
len -= avail;
while (len >= sizeof(mctx->block)) {
memcpy(mctx->block, data, sizeof(mctx->block));
md5_transform_helper(mctx);
data += sizeof(mctx->block);
len -= sizeof(mctx->block);
}
memcpy(mctx->block, data, len);
return 0;
}
static int md5_final(struct shash_desc *desc, u8 *out)
{
struct md5_state *mctx = shash_desc_ctx(desc);
const unsigned int offset = mctx->byte_count & 0x3f;
char *p = (char *)mctx->block + offset;
int padding = 56 - (offset + 1);
*p++ = 0x80;
if (padding < 0) {
memset(p, 0x00, padding + sizeof (u64));
md5_transform_helper(mctx);
p = (char *)mctx->block;
padding = 56;
}
memset(p, 0, padding);
mctx->block[14] = mctx->byte_count << 3;
mctx->block[15] = mctx->byte_count >> 29;
le32_to_cpu_array(mctx->block, (sizeof(mctx->block) -
sizeof(u64)) / sizeof(u32));
md5_transform(mctx->hash, mctx->block);
cpu_to_le32_array(mctx->hash, sizeof(mctx->hash) / sizeof(u32));
memcpy(out, mctx->hash, sizeof(mctx->hash));
memset(mctx, 0, sizeof(*mctx));
return 0;
}
static int md5_export(struct shash_desc *desc, void *out)
{
struct md5_state *ctx = shash_desc_ctx(desc);
memcpy(out, ctx, sizeof(*ctx));
return 0;
}
static int md5_import(struct shash_desc *desc, const void *in)
{
struct md5_state *ctx = shash_desc_ctx(desc);
memcpy(ctx, in, sizeof(*ctx));
return 0;
}
static struct shash_alg alg = {
.digestsize = MD5_DIGEST_SIZE,
.init = md5_init,
.update = md5_update,
.final = md5_final,
.export = md5_export,
.import = md5_import,
.descsize = sizeof(struct md5_state),
.statesize = sizeof(struct md5_state),
.base = {
.cra_name = "md5",
.cra_flags = CRYPTO_ALG_TYPE_SHASH,
.cra_blocksize = MD5_HMAC_BLOCK_SIZE,
.cra_module = THIS_MODULE,
}
};
static int __init md5_mod_init(void)
{
return crypto_register_shash(&alg);
}
static void __exit md5_mod_fini(void)
{
crypto_unregister_shash(&alg);
}
module_init(md5_mod_init);
module_exit(md5_mod_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MD5 Message Digest Algorithm");
MODULE_ALIAS_CRYPTO("md5");
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