https://github.com/torvalds/linux
Revision df17277b2a85c00f5710e33ce238ba4114687a28 authored by Mike Rapoport on 01 June 2019, 05:30:33 UTC, committed by Linus Torvalds on 01 June 2019, 22:51:31 UTC
When get_user_pages*() is called with pages = NULL, the processing of VM_FAULT_RETRY terminates early without actually retrying to fault-in all the pages. If the pages in the requested range belong to a VMA that has userfaultfd registered, handle_userfault() returns VM_FAULT_RETRY *after* user space has populated the page, but for the gup pre-fault case there's no actual retry and the caller will get no pages although they are present. This issue was uncovered when running post-copy memory restore in CRIU after d9c9ce34ed5c ("x86/fpu: Fault-in user stack if copy_fpstate_to_sigframe() fails"). After this change, the copying of FPU state to the sigframe switched from copy_to_user() variants which caused a real page fault to get_user_pages() with pages parameter set to NULL. In post-copy mode of CRIU, the destination memory is managed with userfaultfd and lack of the retry for pre-fault case in get_user_pages() causes a crash of the restored process. Making the pre-fault behavior of get_user_pages() the same as the "normal" one fixes the issue. Link: http://lkml.kernel.org/r/1557844195-18882-1-git-send-email-rppt@linux.ibm.com Fixes: d9c9ce34ed5c ("x86/fpu: Fault-in user stack if copy_fpstate_to_sigframe() fails") Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Tested-by: Andrei Vagin <avagin@gmail.com> [https://travis-ci.org/avagin/linux/builds/533184940] Tested-by: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Borislav Petkov <bp@suse.de> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent b9fba67
Tip revision: df17277b2a85c00f5710e33ce238ba4114687a28 authored by Mike Rapoport on 01 June 2019, 05:30:33 UTC
mm/gup: continue VM_FAULT_RETRY processing even for pre-faults
mm/gup: continue VM_FAULT_RETRY processing even for pre-faults
Tip revision: df17277
crc32c_generic.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Cryptographic API.
*
* CRC32C chksum
*
*@Article{castagnoli-crc,
* author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
* title = {{Optimization of Cyclic Redundancy-Check Codes with 24
* and 32 Parity Bits}},
* journal = IEEE Transactions on Communication,
* year = {1993},
* volume = {41},
* number = {6},
* pages = {},
* month = {June},
*}
* Used by the iSCSI driver, possibly others, and derived from the
* the iscsi-crc.c module of the linux-iscsi driver at
* http://linux-iscsi.sourceforge.net.
*
* Following the example of lib/crc32, this function is intended to be
* flexible and useful for all users. Modules that currently have their
* own crc32c, but hopefully may be able to use this one are:
* net/sctp (please add all your doco to here if you change to
* use this one!)
* <endoflist>
*
* Copyright (c) 2004 Cisco Systems, Inc.
* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
*/
#include <asm/unaligned.h>
#include <crypto/internal/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/crc32.h>
#define CHKSUM_BLOCK_SIZE 1
#define CHKSUM_DIGEST_SIZE 4
struct chksum_ctx {
u32 key;
};
struct chksum_desc_ctx {
u32 crc;
};
/*
* Steps through buffer one byte at at time, calculates reflected
* crc using table.
*/
static int chksum_init(struct shash_desc *desc)
{
struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
ctx->crc = mctx->key;
return 0;
}
/*
* Setting the seed allows arbitrary accumulators and flexible XOR policy
* If your algorithm starts with ~0, then XOR with ~0 before you set
* the seed.
*/
static int chksum_setkey(struct crypto_shash *tfm, const u8 *key,
unsigned int keylen)
{
struct chksum_ctx *mctx = crypto_shash_ctx(tfm);
if (keylen != sizeof(mctx->key)) {
crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
return -EINVAL;
}
mctx->key = get_unaligned_le32(key);
return 0;
}
static int chksum_update(struct shash_desc *desc, const u8 *data,
unsigned int length)
{
struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
ctx->crc = __crc32c_le(ctx->crc, data, length);
return 0;
}
static int chksum_final(struct shash_desc *desc, u8 *out)
{
struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
put_unaligned_le32(~ctx->crc, out);
return 0;
}
static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)
{
put_unaligned_le32(~__crc32c_le(*crcp, data, len), out);
return 0;
}
static int chksum_finup(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
return __chksum_finup(&ctx->crc, data, len, out);
}
static int chksum_digest(struct shash_desc *desc, const u8 *data,
unsigned int length, u8 *out)
{
struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
return __chksum_finup(&mctx->key, data, length, out);
}
static int crc32c_cra_init(struct crypto_tfm *tfm)
{
struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
mctx->key = ~0;
return 0;
}
static struct shash_alg alg = {
.digestsize = CHKSUM_DIGEST_SIZE,
.setkey = chksum_setkey,
.init = chksum_init,
.update = chksum_update,
.final = chksum_final,
.finup = chksum_finup,
.digest = chksum_digest,
.descsize = sizeof(struct chksum_desc_ctx),
.base = {
.cra_name = "crc32c",
.cra_driver_name = "crc32c-generic",
.cra_priority = 100,
.cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
.cra_blocksize = CHKSUM_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct chksum_ctx),
.cra_module = THIS_MODULE,
.cra_init = crc32c_cra_init,
}
};
static int __init crc32c_mod_init(void)
{
return crypto_register_shash(&alg);
}
static void __exit crc32c_mod_fini(void)
{
crypto_unregister_shash(&alg);
}
subsys_initcall(crc32c_mod_init);
module_exit(crc32c_mod_fini);
MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CRYPTO("crc32c");
MODULE_ALIAS_CRYPTO("crc32c-generic");
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