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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
![Andrea Righi](/assets/img/avatar_default.png)
Using kmalloc() to allocate the decompression workspace for zstd may
trigger the following warning when large modules are loaded (i.e., xfs):
[ 2.961884] WARNING: CPU: 1 PID: 254 at mm/page_alloc.c:4453 __alloc_pages+0x2c3/0x350
...
[ 2.989033] Call Trace:
[ 2.989841] <TASK>
[ 2.990614] ? show_regs+0x6d/0x80
[ 2.991573] ? __warn+0x89/0x160
[ 2.992485] ? __alloc_pages+0x2c3/0x350
[ 2.993520] ? report_bug+0x17e/0x1b0
[ 2.994506] ? handle_bug+0x51/0xa0
[ 2.995474] ? exc_invalid_op+0x18/0x80
[ 2.996469] ? asm_exc_invalid_op+0x1b/0x20
[ 2.997530] ? module_zstd_decompress+0xdc/0x2a0
[ 2.998665] ? __alloc_pages+0x2c3/0x350
[ 2.999695] ? module_zstd_decompress+0xdc/0x2a0
[ 3.000821] __kmalloc_large_node+0x7a/0x150
[ 3.001920] __kmalloc+0xdb/0x170
[ 3.002824] module_zstd_decompress+0xdc/0x2a0
[ 3.003857] module_decompress+0x37/0xc0
[ 3.004688] init_module_from_file+0xd0/0x100
[ 3.005668] idempotent_init_module+0x11c/0x2b0
[ 3.006632] __x64_sys_finit_module+0x64/0xd0
[ 3.007568] do_syscall_64+0x59/0x90
[ 3.008373] ? ksys_read+0x73/0x100
[ 3.009395] ? exit_to_user_mode_prepare+0x30/0xb0
[ 3.010531] ? syscall_exit_to_user_mode+0x37/0x60
[ 3.011662] ? do_syscall_64+0x68/0x90
[ 3.012511] ? do_syscall_64+0x68/0x90
[ 3.013364] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
However, continuous physical memory does not seem to be required in
module_zstd_decompress(), so use vmalloc() instead, to prevent the
warning and avoid potential failures at loading compressed modules.
Fixes: 169a58ad82
("module/decompress: Support zstd in-kernel decompression")
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
368 lines
7.8 KiB
C
368 lines
7.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright 2021 Google LLC.
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*/
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#include <linux/init.h>
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#include <linux/highmem.h>
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#include <linux/kobject.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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#include <linux/vmalloc.h>
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#include "internal.h"
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static int module_extend_max_pages(struct load_info *info, unsigned int extent)
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{
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struct page **new_pages;
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new_pages = kvmalloc_array(info->max_pages + extent,
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sizeof(info->pages), GFP_KERNEL);
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if (!new_pages)
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return -ENOMEM;
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memcpy(new_pages, info->pages, info->max_pages * sizeof(info->pages));
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kvfree(info->pages);
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info->pages = new_pages;
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info->max_pages += extent;
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return 0;
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}
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static struct page *module_get_next_page(struct load_info *info)
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{
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struct page *page;
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int error;
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if (info->max_pages == info->used_pages) {
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error = module_extend_max_pages(info, info->used_pages);
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if (error)
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return ERR_PTR(error);
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}
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page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
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if (!page)
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return ERR_PTR(-ENOMEM);
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info->pages[info->used_pages++] = page;
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return page;
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}
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#if defined(CONFIG_MODULE_COMPRESS_GZIP)
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#include <linux/zlib.h>
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#define MODULE_COMPRESSION gzip
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#define MODULE_DECOMPRESS_FN module_gzip_decompress
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/*
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* Calculate length of the header which consists of signature, header
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* flags, time stamp and operating system ID (10 bytes total), plus
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* an optional filename.
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*/
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static size_t module_gzip_header_len(const u8 *buf, size_t size)
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{
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const u8 signature[] = { 0x1f, 0x8b, 0x08 };
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size_t len = 10;
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if (size < len || memcmp(buf, signature, sizeof(signature)))
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return 0;
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if (buf[3] & 0x08) {
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do {
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/*
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* If we can't find the end of the file name we must
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* be dealing with a corrupted file.
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*/
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if (len == size)
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return 0;
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} while (buf[len++] != '\0');
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}
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return len;
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}
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static ssize_t module_gzip_decompress(struct load_info *info,
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const void *buf, size_t size)
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{
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struct z_stream_s s = { 0 };
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size_t new_size = 0;
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size_t gzip_hdr_len;
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ssize_t retval;
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int rc;
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gzip_hdr_len = module_gzip_header_len(buf, size);
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if (!gzip_hdr_len) {
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pr_err("not a gzip compressed module\n");
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return -EINVAL;
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}
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s.next_in = buf + gzip_hdr_len;
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s.avail_in = size - gzip_hdr_len;
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s.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
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if (!s.workspace)
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return -ENOMEM;
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rc = zlib_inflateInit2(&s, -MAX_WBITS);
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if (rc != Z_OK) {
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pr_err("failed to initialize decompressor: %d\n", rc);
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retval = -EINVAL;
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goto out;
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}
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do {
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struct page *page = module_get_next_page(info);
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if (IS_ERR(page)) {
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retval = PTR_ERR(page);
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goto out_inflate_end;
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}
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s.next_out = kmap_local_page(page);
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s.avail_out = PAGE_SIZE;
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rc = zlib_inflate(&s, 0);
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kunmap_local(s.next_out);
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new_size += PAGE_SIZE - s.avail_out;
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} while (rc == Z_OK);
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if (rc != Z_STREAM_END) {
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pr_err("decompression failed with status %d\n", rc);
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retval = -EINVAL;
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goto out_inflate_end;
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}
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retval = new_size;
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out_inflate_end:
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zlib_inflateEnd(&s);
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out:
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kfree(s.workspace);
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return retval;
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}
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#elif defined(CONFIG_MODULE_COMPRESS_XZ)
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#include <linux/xz.h>
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#define MODULE_COMPRESSION xz
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#define MODULE_DECOMPRESS_FN module_xz_decompress
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static ssize_t module_xz_decompress(struct load_info *info,
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const void *buf, size_t size)
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{
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static const u8 signature[] = { 0xfd, '7', 'z', 'X', 'Z', 0 };
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struct xz_dec *xz_dec;
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struct xz_buf xz_buf;
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enum xz_ret xz_ret;
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size_t new_size = 0;
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ssize_t retval;
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if (size < sizeof(signature) ||
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memcmp(buf, signature, sizeof(signature))) {
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pr_err("not an xz compressed module\n");
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return -EINVAL;
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}
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xz_dec = xz_dec_init(XZ_DYNALLOC, (u32)-1);
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if (!xz_dec)
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return -ENOMEM;
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xz_buf.in_size = size;
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xz_buf.in = buf;
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xz_buf.in_pos = 0;
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do {
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struct page *page = module_get_next_page(info);
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if (IS_ERR(page)) {
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retval = PTR_ERR(page);
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goto out;
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}
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xz_buf.out = kmap_local_page(page);
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xz_buf.out_pos = 0;
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xz_buf.out_size = PAGE_SIZE;
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xz_ret = xz_dec_run(xz_dec, &xz_buf);
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kunmap_local(xz_buf.out);
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new_size += xz_buf.out_pos;
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} while (xz_buf.out_pos == PAGE_SIZE && xz_ret == XZ_OK);
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if (xz_ret != XZ_STREAM_END) {
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pr_err("decompression failed with status %d\n", xz_ret);
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retval = -EINVAL;
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goto out;
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}
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retval = new_size;
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out:
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xz_dec_end(xz_dec);
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return retval;
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}
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#elif defined(CONFIG_MODULE_COMPRESS_ZSTD)
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#include <linux/zstd.h>
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#define MODULE_COMPRESSION zstd
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#define MODULE_DECOMPRESS_FN module_zstd_decompress
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static ssize_t module_zstd_decompress(struct load_info *info,
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const void *buf, size_t size)
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{
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static const u8 signature[] = { 0x28, 0xb5, 0x2f, 0xfd };
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ZSTD_outBuffer zstd_dec;
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ZSTD_inBuffer zstd_buf;
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zstd_frame_header header;
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size_t wksp_size;
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void *wksp = NULL;
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ZSTD_DStream *dstream;
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size_t ret;
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size_t new_size = 0;
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int retval;
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if (size < sizeof(signature) ||
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memcmp(buf, signature, sizeof(signature))) {
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pr_err("not a zstd compressed module\n");
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return -EINVAL;
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}
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zstd_buf.src = buf;
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zstd_buf.pos = 0;
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zstd_buf.size = size;
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ret = zstd_get_frame_header(&header, zstd_buf.src, zstd_buf.size);
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if (ret != 0) {
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pr_err("ZSTD-compressed data has an incomplete frame header\n");
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retval = -EINVAL;
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goto out;
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}
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if (header.windowSize > (1 << ZSTD_WINDOWLOG_MAX)) {
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pr_err("ZSTD-compressed data has too large a window size\n");
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retval = -EINVAL;
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goto out;
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}
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wksp_size = zstd_dstream_workspace_bound(header.windowSize);
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wksp = vmalloc(wksp_size);
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if (!wksp) {
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retval = -ENOMEM;
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goto out;
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}
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dstream = zstd_init_dstream(header.windowSize, wksp, wksp_size);
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if (!dstream) {
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pr_err("Can't initialize ZSTD stream\n");
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retval = -ENOMEM;
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goto out;
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}
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do {
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struct page *page = module_get_next_page(info);
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if (IS_ERR(page)) {
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retval = PTR_ERR(page);
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goto out;
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}
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zstd_dec.dst = kmap_local_page(page);
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zstd_dec.pos = 0;
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zstd_dec.size = PAGE_SIZE;
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ret = zstd_decompress_stream(dstream, &zstd_dec, &zstd_buf);
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kunmap_local(zstd_dec.dst);
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retval = zstd_get_error_code(ret);
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if (retval)
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break;
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new_size += zstd_dec.pos;
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} while (zstd_dec.pos == PAGE_SIZE && ret != 0);
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if (retval) {
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pr_err("ZSTD-decompression failed with status %d\n", retval);
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retval = -EINVAL;
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goto out;
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}
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retval = new_size;
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out:
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vfree(wksp);
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return retval;
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}
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#else
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#error "Unexpected configuration for CONFIG_MODULE_DECOMPRESS"
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#endif
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int module_decompress(struct load_info *info, const void *buf, size_t size)
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{
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unsigned int n_pages;
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ssize_t data_size;
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int error;
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#if defined(CONFIG_MODULE_STATS)
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info->compressed_len = size;
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#endif
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/*
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* Start with number of pages twice as big as needed for
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* compressed data.
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*/
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n_pages = DIV_ROUND_UP(size, PAGE_SIZE) * 2;
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error = module_extend_max_pages(info, n_pages);
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data_size = MODULE_DECOMPRESS_FN(info, buf, size);
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if (data_size < 0) {
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error = data_size;
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goto err;
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}
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info->hdr = vmap(info->pages, info->used_pages, VM_MAP, PAGE_KERNEL);
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if (!info->hdr) {
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error = -ENOMEM;
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goto err;
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}
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info->len = data_size;
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return 0;
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err:
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module_decompress_cleanup(info);
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return error;
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}
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void module_decompress_cleanup(struct load_info *info)
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{
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int i;
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if (info->hdr)
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vunmap(info->hdr);
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for (i = 0; i < info->used_pages; i++)
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__free_page(info->pages[i]);
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kvfree(info->pages);
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info->pages = NULL;
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info->max_pages = info->used_pages = 0;
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}
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#ifdef CONFIG_SYSFS
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static ssize_t compression_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sysfs_emit(buf, __stringify(MODULE_COMPRESSION) "\n");
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}
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static struct kobj_attribute module_compression_attr = __ATTR_RO(compression);
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static int __init module_decompress_sysfs_init(void)
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{
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int error;
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error = sysfs_create_file(&module_kset->kobj,
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&module_compression_attr.attr);
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if (error)
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pr_warn("Failed to create 'compression' attribute");
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return 0;
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}
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late_initcall(module_decompress_sysfs_init);
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#endif
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