Revision a4aeaa06d45e90f9b279f0b09de84bd00006e733 authored by Yang Shi on 28 October 2021, 21:36:30 UTC, committed by Linus Torvalds on 29 October 2021, 00:18:55 UTC
The read-only THP for filesystems will collapse THP for files opened readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB misses for large text segments. But it doesn't restrict the file types so a THP could be collapsed for a non-regular file, for example, block device, if it is opened readonly and mapped with EXEC permission. This may cause bugs, like [1] and [2]. This is definitely not the intended usecase, so just collapse THP for regular files in order to close the attack surface. [shy828301@gmail.com: fix vm_file check [3]] Link: https://lore.kernel.org/lkml/CACkBjsYwLYLRmX8GpsDpMthagWOjWWrNxqY6ZLNQVr6yx+f5vA@mail.gmail.com/ [1] Link: https://lore.kernel.org/linux-mm/000000000000c6a82505ce284e4c@google.com/ [2] Link: https://lkml.kernel.org/r/CAHbLzkqTW9U3VvTu1Ki5v_cLRC9gHW+znBukg_ycergE0JWj-A@mail.gmail.com [3] Link: https://lkml.kernel.org/r/20211027195221.3825-1-shy828301@gmail.com Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Yang Shi <shy828301@gmail.com> Reported-by: Hao Sun <sunhao.th@gmail.com> Reported-by: syzbot+aae069be1de40fb11825@syzkaller.appspotmail.com Cc: Matthew Wilcox <willy@infradead.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Song Liu <songliubraving@fb.com> Cc: Andrea Righi <andrea.righi@canonical.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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proc.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Scatterlist Cryptographic API.
*
* Procfs information.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
* Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
*/
#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 "internal.h"
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 : %u\n", refcount_read(&alg->cra_refcnt));
seq_printf(m, "selftest : %s\n",
(alg->cra_flags & CRYPTO_ALG_TESTED) ?
"passed" : "unknown");
seq_printf(m, "internal : %s\n",
(alg->cra_flags & CRYPTO_ALG_INTERNAL) ?
"yes" : "no");
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) {
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
};
void __init crypto_init_proc(void)
{
proc_create_seq("crypto", 0, NULL, &crypto_seq_ops);
}
void __exit crypto_exit_proc(void)
{
remove_proc_entry("crypto", NULL);
}
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