/* * Squashfs - a compressed read only filesystem for Linux * * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 * Phillip Lougher * * 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, * or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. * * fragment.c */ /* * This file implements code to handle compressed fragments (tail-end packed * datablocks). * * Regular files contain a fragment index which is mapped to a fragment * location on disk and compressed size using a fragment lookup table. * Like everything in Squashfs this fragment lookup table is itself stored * compressed into metadata blocks. A second index table is used to locate * these. This second index table for speed of access (and because it * is small) is read at mount time and cached in memory. */ #include #include #include #include "squashfs_fs.h" #include "squashfs_fs_sb.h" #include "squashfs.h" /* * Look-up fragment using the fragment index table. Return the on disk * location of the fragment and its compressed size */ int squashfs_frag_lookup(struct super_block *sb, unsigned int fragment, u64 *fragment_block) { struct squashfs_sb_info *msblk = sb->s_fs_info; int block = SQUASHFS_FRAGMENT_INDEX(fragment); int offset = SQUASHFS_FRAGMENT_INDEX_OFFSET(fragment); u64 start_block = le64_to_cpu(msblk->fragment_index[block]); struct squashfs_fragment_entry fragment_entry; int size; size = squashfs_read_metadata(sb, &fragment_entry, &start_block, &offset, sizeof(fragment_entry)); if (size < 0) return size; *fragment_block = le64_to_cpu(fragment_entry.start_block); size = le32_to_cpu(fragment_entry.size); return size; } /* * Read the uncompressed fragment lookup table indexes off disk into memory */ __le64 *squashfs_read_fragment_index_table(struct super_block *sb, u64 fragment_table_start, u64 next_table, unsigned int fragments) { unsigned int length = SQUASHFS_FRAGMENT_INDEX_BYTES(fragments); __le64 *table; /* * Sanity check, length bytes should not extend into the next table - * this check also traps instances where fragment_table_start is * incorrectly larger than the next table start */ if (fragment_table_start + length > next_table) return ERR_PTR(-EINVAL); table = squashfs_read_table(sb, fragment_table_start, length); /* * table[0] points to the first fragment table metadata block, this * should be less than fragment_table_start */ if (!IS_ERR(table) && le64_to_cpu(table[0]) >= fragment_table_start) { kfree(table); return ERR_PTR(-EINVAL); } return table; } id=966d2b04e070bc040319aaebfec09e0144dc3341'>net/fou.h
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authorDouglas Miller <dougmill@linux.vnet.ibm.com>2017-01-28 06:42:20 -0600
committerTejun Heo <tj@kernel.org>2017-01-28 07:49:42 -0500
commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch)
tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /include/net/fou.h
parent1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff)
percpu-refcount: fix reference leak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'include/net/fou.h')