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Revision 50338b889dc504c69e0cb316ac92d1b9e51f3c8a authored by Török Edwin on 15 June 2011, 21:06:14 UTC, committed by Al Viro on 16 June 2011, 15:27:39 UTC 
fix wrong iput on d_inode introduced by e6bc45d65d
 
Git bisection shows that commit e6bc45d65df8599fdbae73be9cec4ceed274db53 causes
BUG_ONs under high I/O load:

kernel BUG at fs/inode.c:1368!
[ 2862.501007] Call Trace:
[ 2862.501007]  [<ffffffff811691d8>] d_kill+0xf8/0x140
[ 2862.501007]  [<ffffffff81169c19>] dput+0xc9/0x190
[ 2862.501007]  [<ffffffff8115577f>] fput+0x15f/0x210
[ 2862.501007]  [<ffffffff81152171>] filp_close+0x61/0x90
[ 2862.501007]  [<ffffffff81152251>] sys_close+0xb1/0x110
[ 2862.501007]  [<ffffffff814c14fb>] system_call_fastpath+0x16/0x1b

A reliable way to reproduce this bug is:
Login to KDE, run 'rsnapshot sync', and apt-get install openjdk-6-jdk,
and apt-get remove openjdk-6-jdk.

The buggy part of the patch is this:
	struct inode *inode = NULL;
.....
-               if (nd.last.name[nd.last.len])
-                       goto slashes;
                inode = dentry->d_inode;
-               if (inode)
-                       ihold(inode);
+               if (nd.last.name[nd.last.len] || !inode)
+                       goto slashes;
+               ihold(inode)
...
	if (inode)
		iput(inode);	/* truncate the inode here */

If nd.last.name[nd.last.len] is nonzero (and thus goto slashes branch is taken),
and dentry->d_inode is non-NULL, then this code now does an additional iput on
the inode, which is wrong.

Fix this by only setting the inode variable if nd.last.name[nd.last.len] is 0.

Reference: https://lkml.org/lkml/2011/6/15/50
Reported-by: Norbert Preining <preining@logic.at>
Reported-by: Török Edwin <edwintorok@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Török Edwin <edwintorok@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1 parent a685e08
Raw File
tcrypt.h 
/*
 * Quick & dirty crypto testing module.
 *
 * This will only exist until we have a better testing mechanism
 * (e.g. a char device).
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2002 Jean-Francois Dive <jef@linuxbe.org>
 * Copyright (c) 2007 Nokia Siemens Networks
 *
 * 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.
 *
 */
#ifndef _CRYPTO_TCRYPT_H
#define _CRYPTO_TCRYPT_H

struct cipher_speed_template {
	const char *key;
	unsigned int klen;
};

struct hash_speed {
	unsigned int blen;	/* buffer length */
	unsigned int plen;	/* per-update length */
	unsigned int klen;	/* key length */
};

/*
 * DES test vectors.
 */
#define DES3_SPEED_VECTORS	1

static struct cipher_speed_template des3_speed_template[] = {
	{
		.key	= "\x01\x23\x45\x67\x89\xab\xcd\xef"
			  "\x55\x55\x55\x55\x55\x55\x55\x55"
			  "\xfe\xdc\xba\x98\x76\x54\x32\x10",
		.klen	= 24,
	}
};

/*
 * Cipher speed tests
 */
static u8 speed_template_8[] = {8, 0};
static u8 speed_template_24[] = {24, 0};
static u8 speed_template_8_32[] = {8, 32, 0};
static u8 speed_template_16_32[] = {16, 32, 0};
static u8 speed_template_16_24_32[] = {16, 24, 32, 0};
static u8 speed_template_32_40_48[] = {32, 40, 48, 0};
static u8 speed_template_32_48_64[] = {32, 48, 64, 0};

/*
 * Digest speed tests
 */
static struct hash_speed generic_hash_speed_template[] = {
	{ .blen = 16,	.plen = 16, },
	{ .blen = 64,	.plen = 16, },
	{ .blen = 64,	.plen = 64, },
	{ .blen = 256,	.plen = 16, },
	{ .blen = 256,	.plen = 64, },
	{ .blen = 256,	.plen = 256, },
	{ .blen = 1024,	.plen = 16, },
	{ .blen = 1024,	.plen = 256, },
	{ .blen = 1024,	.plen = 1024, },
	{ .blen = 2048,	.plen = 16, },
	{ .blen = 2048,	.plen = 256, },
	{ .blen = 2048,	.plen = 1024, },
	{ .blen = 2048,	.plen = 2048, },
	{ .blen = 4096,	.plen = 16, },
	{ .blen = 4096,	.plen = 256, },
	{ .blen = 4096,	.plen = 1024, },
	{ .blen = 4096,	.plen = 4096, },
	{ .blen = 8192,	.plen = 16, },
	{ .blen = 8192,	.plen = 256, },
	{ .blen = 8192,	.plen = 1024, },
	{ .blen = 8192,	.plen = 4096, },
	{ .blen = 8192,	.plen = 8192, },

	/* End marker */
	{  .blen = 0,	.plen = 0, }
};

static struct hash_speed hash_speed_template_16[] = {
	{ .blen = 16,	.plen = 16,	.klen = 16, },
	{ .blen = 64,	.plen = 16,	.klen = 16, },
	{ .blen = 64,	.plen = 64,	.klen = 16, },
	{ .blen = 256,	.plen = 16,	.klen = 16, },
	{ .blen = 256,	.plen = 64,	.klen = 16, },
	{ .blen = 256,	.plen = 256,	.klen = 16, },
	{ .blen = 1024,	.plen = 16,	.klen = 16, },
	{ .blen = 1024,	.plen = 256,	.klen = 16, },
	{ .blen = 1024,	.plen = 1024,	.klen = 16, },
	{ .blen = 2048,	.plen = 16,	.klen = 16, },
	{ .blen = 2048,	.plen = 256,	.klen = 16, },
	{ .blen = 2048,	.plen = 1024,	.klen = 16, },
	{ .blen = 2048,	.plen = 2048,	.klen = 16, },
	{ .blen = 4096,	.plen = 16,	.klen = 16, },
	{ .blen = 4096,	.plen = 256,	.klen = 16, },
	{ .blen = 4096,	.plen = 1024,	.klen = 16, },
	{ .blen = 4096,	.plen = 4096,	.klen = 16, },
	{ .blen = 8192,	.plen = 16,	.klen = 16, },
	{ .blen = 8192,	.plen = 256,	.klen = 16, },
	{ .blen = 8192,	.plen = 1024,	.klen = 16, },
	{ .blen = 8192,	.plen = 4096,	.klen = 16, },
	{ .blen = 8192,	.plen = 8192,	.klen = 16, },

	/* End marker */
	{  .blen = 0,	.plen = 0,	.klen = 0, }
};

#endif	/* _CRYPTO_TCRYPT_H */
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