Revision eecc1e426d681351a6026a7d3e7d225f38955b6c authored by Hugh Dickins on 12 January 2014, 09:25:21 UTC, committed by Linus Torvalds on 12 January 2014, 09:47:15 UTC
We see General Protection Fault on RSI in copy_page_rep: that RSI is what you get from a NULL struct page pointer. RIP: 0010:[<ffffffff81154955>] [<ffffffff81154955>] copy_page_rep+0x5/0x10 RSP: 0000:ffff880136e15c00 EFLAGS: 00010286 RAX: ffff880000000000 RBX: ffff880136e14000 RCX: 0000000000000200 RDX: 6db6db6db6db6db7 RSI: db73880000000000 RDI: ffff880dd0c00000 RBP: ffff880136e15c18 R08: 0000000000000200 R09: 000000000005987c R10: 000000000005987c R11: 0000000000000200 R12: 0000000000000001 R13: ffffea00305aa000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f195752f700(0000) GS:ffff880c7fc20000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000093010000 CR3: 00000001458e1000 CR4: 00000000000027e0 Call Trace: copy_user_huge_page+0x93/0xab do_huge_pmd_wp_page+0x710/0x815 handle_mm_fault+0x15d8/0x1d70 __do_page_fault+0x14d/0x840 do_page_fault+0x2f/0x90 page_fault+0x22/0x30 do_huge_pmd_wp_page() tests is_huge_zero_pmd(orig_pmd) four times: but since shrink_huge_zero_page() can free the huge_zero_page, and we have no hold of our own on it here (except where the fourth test holds page_table_lock and has checked pmd_same), it's possible for it to answer yes the first time, but no to the second or third test. Change all those last three to tests for NULL page. (Note: this is not the same issue as trinity's DEBUG_PAGEALLOC BUG in copy_page_rep with RSI: ffff88009c422000, reported by Sasha Levin in https://lkml.org/lkml/2013/3/29/103. I believe that one is due to the source page being split, and a tail page freed, while copy is in progress; and not a problem without DEBUG_PAGEALLOC, since the pmd_same check will prevent a miscopy from being made visible.) Fixes: 97ae17497e99 ("thp: implement refcounting for huge zero page") Signed-off-by: Hugh Dickins <hughd@google.com> Cc: stable@vger.kernel.org # v3.10 v3.11 v3.12 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 518d00b
proc.c
/*
* Scatterlist Cryptographic API.
*
* Procfs information.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
* Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.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 <linux/atomic.h>
#include <linux/init.h>
#include <linux/crypto.h>
#include <linux/module.h> /* for module_name() */
#include <linux/rwsem.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/sysctl.h>
#include "internal.h"
#ifdef CONFIG_CRYPTO_FIPS
static struct ctl_table crypto_sysctl_table[] = {
{
.procname = "fips_enabled",
.data = &fips_enabled,
.maxlen = sizeof(int),
.mode = 0444,
.proc_handler = proc_dointvec
},
{}
};
static struct ctl_table crypto_dir_table[] = {
{
.procname = "crypto",
.mode = 0555,
.child = crypto_sysctl_table
},
{}
};
static struct ctl_table_header *crypto_sysctls;
static void crypto_proc_fips_init(void)
{
crypto_sysctls = register_sysctl_table(crypto_dir_table);
}
static void crypto_proc_fips_exit(void)
{
if (crypto_sysctls)
unregister_sysctl_table(crypto_sysctls);
}
#else
#define crypto_proc_fips_init()
#define crypto_proc_fips_exit()
#endif
static void *c_start(struct seq_file *m, loff_t *pos)
{
down_read(&crypto_alg_sem);
return seq_list_start(&crypto_alg_list, *pos);
}
static void *c_next(struct seq_file *m, void *p, loff_t *pos)
{
return seq_list_next(p, &crypto_alg_list, pos);
}
static void c_stop(struct seq_file *m, void *p)
{
up_read(&crypto_alg_sem);
}
static int c_show(struct seq_file *m, void *p)
{
struct crypto_alg *alg = list_entry(p, struct crypto_alg, cra_list);
seq_printf(m, "name : %s\n", alg->cra_name);
seq_printf(m, "driver : %s\n", alg->cra_driver_name);
seq_printf(m, "module : %s\n", module_name(alg->cra_module));
seq_printf(m, "priority : %d\n", alg->cra_priority);
seq_printf(m, "refcnt : %d\n", atomic_read(&alg->cra_refcnt));
seq_printf(m, "selftest : %s\n",
(alg->cra_flags & CRYPTO_ALG_TESTED) ?
"passed" : "unknown");
if (alg->cra_flags & CRYPTO_ALG_LARVAL) {
seq_printf(m, "type : larval\n");
seq_printf(m, "flags : 0x%x\n", alg->cra_flags);
goto out;
}
if (alg->cra_type && alg->cra_type->show) {
alg->cra_type->show(m, alg);
goto out;
}
switch (alg->cra_flags & (CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_LARVAL)) {
case CRYPTO_ALG_TYPE_CIPHER:
seq_printf(m, "type : cipher\n");
seq_printf(m, "blocksize : %u\n", alg->cra_blocksize);
seq_printf(m, "min keysize : %u\n",
alg->cra_cipher.cia_min_keysize);
seq_printf(m, "max keysize : %u\n",
alg->cra_cipher.cia_max_keysize);
break;
case CRYPTO_ALG_TYPE_COMPRESS:
seq_printf(m, "type : compression\n");
break;
default:
seq_printf(m, "type : unknown\n");
break;
}
out:
seq_putc(m, '\n');
return 0;
}
static const struct seq_operations crypto_seq_ops = {
.start = c_start,
.next = c_next,
.stop = c_stop,
.show = c_show
};
static int crypto_info_open(struct inode *inode, struct file *file)
{
return seq_open(file, &crypto_seq_ops);
}
static const struct file_operations proc_crypto_ops = {
.open = crypto_info_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release
};
void __init crypto_init_proc(void)
{
proc_create("crypto", 0, NULL, &proc_crypto_ops);
crypto_proc_fips_init();
}
void __exit crypto_exit_proc(void)
{
crypto_proc_fips_exit();
remove_proc_entry("crypto", NULL);
}
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