Re: BUG at kmem_cache_alloc

[Dave Jones]

On Thu, Mar 28, 2013 at 03:49:37AM -0400, CAI Qian wrote:
 
 > While reproducing this, it triggered something else with SLUB_DEBUG_ON.
 > CAI Qian
 > 
 > [87295.499233] general protection fault: 0000 [#1] SMP 
 > [87295.500228] Modules linked in: binfmt_misc fuse tun cmtp kernelcapi rfcomm bnep hidp scsi_transport_iscsi nfnetlink ipt_ULOG nfc bluetooth rfkill af_key atm lockd sunrpc nf_conntrack_netbios_ns nf_conntrack_broadcast ipt_MASQUERADE ip6table_mangle ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 iptable_nat nf_nat_ipv4 nf_nat iptable_mangle ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter ip_tables sg kvm_amd kvm microcode amd64_edac_mod edac_mce_amd pcspkr serio_raw edac_core k10temp bnx2x netxen_nic mdio i2c_piix4 i2c_core hpilo shpchp ipmi_si ipmi_msghandler hpwdt xfs libcrc32c sd_mod crc_t10dif sata_svw libata dm_mirror dm_region_hash dm_log dm_mod
 > [87295.515752] CPU 1 
 > [87295.516184] Pid: 23211, comm: trinity-main Tainted: G        W    3.8.4 #4 HP ProLiant BL495c G5  
 > [87295.517810] RIP: 0010:[<ffffffff812e0b43>]  [<ffffffff812e0b43>] rb_next+0x23/0x50
 > [87295.519254] RSP: 0018:ffff880127f5de58  EFLAGS: 00010202
 > [87295.520398] RAX: 6b6b6b6b6b6b6b6b RBX: 0000000000000000 RCX: ffff88014181d9c8
 > [87295.521996] RDX: 6b6b6b6b6b6b6b6b RSI: ffff88014181a6e0 RDI: ffff88014181d9e0
 > [87295.523606] RBP: ffff880127f5de58 R08: 0000000000003d7b R09: 0000000000000008
 > [87295.525201] R10: ffffffff81197360 R11: 0000000000000246 R12: ffff8801314f3180
 > [87295.526793] R13: 0000000000000000 R14: 000000000000000f R15: ffff88014181d9c8
 > [87295.528465] FS:  00007f94bbc0f740(0000) GS:ffff88014fc80000(0000) knlGS:0000000000000000
 > [87295.530271] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 > [87295.531578] CR2: 0000000001f53008 CR3: 00000001129f5000 CR4: 00000000000007e0
 > [87295.533210] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 > [87295.534797] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
 > [87295.536402] Process trinity-main (pid: 23211, threadinfo ffff880127f5c000, task ffff8801418e98a0)
 > [87295.538368] Stack:
 > [87295.538793]  ffff880127f5ded8 ffffffff811f8220 0000000000000008 0000000000003d7b
 > [87295.540579]  ffff880127f50001 ffff8801314f3190 0000000000020000 ffffffff81197360
 > [87295.542313]  ffff880127f5df40 ffff88014181a6e0 ffff880127f5ded8 ffff8801314f3180
 > [87295.543959] Call Trace:
 > [87295.544513]  [<ffffffff811f8220>] sysfs_readdir+0x150/0x280
 > [87295.545774]  [<ffffffff81197360>] ? fillonedir+0x100/0x100
 > [87295.547004]  [<ffffffff81197360>] ? fillonedir+0x100/0x100
 > [87295.548268]  [<ffffffff81197238>] vfs_readdir+0xb8/0xe0
 > [87295.549446]  [<ffffffff811a159b>] ? set_close_on_exec+0x3b/0x70
 > [87295.550832]  [<ffffffff8119758f>] sys_getdents+0x8f/0x110
 > [87295.552068]  [<ffffffff815e6419>] system_call_fastpath+0x16/0x1b
 > [87295.553433] Code: 48 89 70 10 eb a9 66 90 55 48 8b 17 48 89 e5 48 39 d7 74 3b 48 8b 47 08 48 85 c0 75 0e eb 1f 66 0f 1f 84 00 00 00 00 00 48 89 d0 <48> 8b 50 10 48 85 d2 75 f4 5d c3 66 90 48 8b 10 48 89 c7 48 89 
 > [87295.557829] RIP  [<ffffffff812e0b43>] rb_next+0x23/0x50
 > [87295.558960]  RSP <ffff880127f5de58>
 > [87295.560213] ---[ end trace d5f25cc963b1f1d9 ]---
 > [watchdog] Triggering periodic reseed.

That's fixed by the patch below from Ming Lei.


diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 2fbdff6..014ed97 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -280,6 +280,11 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
 	 * sd->s_parent won't change beneath us.
 	 */
 	parent_sd = sd->s_parent;
+	if(!(sd->s_flags & SYSFS_FLAG_REMOVED)) {
+		printk("%s-%d sysfs_dirent use after free: %s-%s\n",
+			__func__, __LINE__, parent_sd->s_name, sd->s_name);
+		dump_stack();
+	}
 
 	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
 		sysfs_put(sd->s_symlink.target_sd);
@@ -962,6 +967,12 @@ static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
 		int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
 			pos->s_parent == parent_sd &&
 			hash == pos->s_hash;
+
+		if ((atomic_read(&pos->s_count) == 1)) {
+			printk("%s-%d sysfs_dirent use after free: %s(%s)-%s, %lld-%u\n",
+				__func__, __LINE__, parent_sd->s_name, pos->s_parent->s_name,
+				pos->s_name, hash, pos->s_hash);
+		}
 		sysfs_put(pos);
 		if (!valid)
 			pos = NULL;
@@ -1020,6 +1031,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 		ino = parent_sd->s_ino;
 		if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
 			filp->f_pos++;
+		else
+			return 0;
 	}
 	if (filp->f_pos == 1) {
 		if (parent_sd->s_parent)
@@ -1028,6 +1041,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 			ino = parent_sd->s_ino;
 		if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
 			filp->f_pos++;
+		else
+			return 0;
 	}
 	mutex_lock(&sysfs_mutex);
 	for (pos = sysfs_dir_pos(ns, parent_sd, filp->f_pos, pos);
@@ -1058,10 +1073,21 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 	return 0;
 }
 
+static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file_inode(file);
+	loff_t ret;
+
+	mutex_lock(&inode->i_mutex);
+	ret = generic_file_llseek(file, offset, whence);
+	mutex_unlock(&inode->i_mutex);
+
+	return ret;
+}
 
 const struct file_operations sysfs_dir_operations = {
 	.read		= generic_read_dir,
 	.readdir	= sysfs_readdir,
 	.release	= sysfs_dir_release,
-	.llseek		= generic_file_llseek,
+	.llseek		= sysfs_dir_llseek,
 };

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