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Message-ID: <20111128181446.2ab784d0@kryten>
Date: Mon, 28 Nov 2011 18:14:46 +1100
From: Anton Blanchard <anton@...ba.org>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: Sasha Levin <levinsasha928@...il.com>,
David Miller <davem@...emloft.net>,
Matt Mackall <mpm@...enic.com>,
Christoph Lameter <cl@...ux-foundation.org>,
Pekka Enberg <penberg@...nel.org>,
linux-mm <linux-mm@...ck.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
netdev <netdev@...r.kernel.org>
Subject: [PATCH] net: Fix corruption in /proc/*/net/dev_mcast
Hi,
> I got the following output when running some tests (I'm not really sure
> what exactly happened when this bug was triggered):
>
> [13850.947279] =============================================================================
> [13850.948024] BUG kmalloc-8: Redzone overwritten
> [13850.948024] -----------------------------------------------------------------------------
> [13850.948024]
> [13850.948024] INFO: 0xffff8800104f6d28-0xffff8800104f6d2b. First byte 0x0 instead of 0xcc
> [13850.948024] INFO: Allocated in __seq_open_private+0x20/0x5e age=4436 cpu=0 pid=17295
> [13850.948024] __slab_alloc.clone.46+0x3e7/0x456
> [13850.948024] __kmalloc+0x8c/0x110
> [13850.948024] __seq_open_private+0x20/0x5e
> [13850.948024] seq_open_net+0x3b/0x5d
> [13850.948024] dev_mc_seq_open+0x15/0x17
> [13850.948024] proc_reg_open+0xad/0x127
I just hit this during my testing. Isn't there another bug lurking?
Anton
--
With slub debugging on I see red zone issues in /proc/*/net/dev_mcast:
=============================================================================
BUG kmalloc-8: Redzone overwritten
-----------------------------------------------------------------------------
INFO: 0xc0000000de9dec48-0xc0000000de9dec4b. First byte 0x0 instead of 0xcc
INFO: Allocated in .__seq_open_private+0x30/0xa0 age=0 cpu=5 pid=3896
.__kmalloc+0x1e0/0x2d0
.__seq_open_private+0x30/0xa0
.seq_open_net+0x60/0xe0
.dev_mc_seq_open+0x4c/0x70
.proc_reg_open+0xd8/0x260
.__dentry_open.clone.11+0x2b8/0x400
.do_last+0xf4/0x950
.path_openat+0xf8/0x480
.do_filp_open+0x48/0xc0
.do_sys_open+0x140/0x250
syscall_exit+0x0/0x40
dev_mc_seq_ops uses dev_seq_start/next/stop but only allocates
sizeof(struct seq_net_private) of private data, whereas it expects
sizeof(struct dev_iter_state):
struct dev_iter_state {
struct seq_net_private p;
unsigned int pos; /* bucket << BUCKET_SPACE + offset */
};
Create dev_seq_open_ops and use it so we don't have to expose
struct dev_iter_state.
Signed-off-by: Anton Blanchard <anton@...ba.org>
---
Index: linux-net/include/linux/netdevice.h
===================================================================
--- linux-net.orig/include/linux/netdevice.h 2011-11-28 17:55:51.469508056 +1100
+++ linux-net/include/linux/netdevice.h 2011-11-28 17:55:52.985535812 +1100
@@ -2536,6 +2536,8 @@ extern void net_disable_timestamp(void)
extern void *dev_seq_start(struct seq_file *seq, loff_t *pos);
extern void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos);
extern void dev_seq_stop(struct seq_file *seq, void *v);
+extern int dev_seq_open_ops(struct inode *inode, struct file *file,
+ const struct seq_operations *ops);
#endif
extern int netdev_class_create_file(struct class_attribute *class_attr);
Index: linux-net/net/core/dev.c
===================================================================
--- linux-net.orig/net/core/dev.c 2011-11-28 17:55:51.481508276 +1100
+++ linux-net/net/core/dev.c 2011-11-28 17:55:52.989535885 +1100
@@ -4282,6 +4282,12 @@ static int dev_seq_open(struct inode *in
sizeof(struct dev_iter_state));
}
+int dev_seq_open_ops(struct inode *inode, struct file *file,
+ const struct seq_operations *ops)
+{
+ return seq_open_net(inode, file, ops, sizeof(struct dev_iter_state));
+}
+
static const struct file_operations dev_seq_fops = {
.owner = THIS_MODULE,
.open = dev_seq_open,
Index: linux-net/net/core/dev_addr_lists.c
===================================================================
--- linux-net.orig/net/core/dev_addr_lists.c 2011-11-28 17:55:47.845441705 +1100
+++ linux-net/net/core/dev_addr_lists.c 2011-11-28 17:55:52.989535885 +1100
@@ -696,8 +696,7 @@ static const struct seq_operations dev_m
static int dev_mc_seq_open(struct inode *inode, struct file *file)
{
- return seq_open_net(inode, file, &dev_mc_seq_ops,
- sizeof(struct seq_net_private));
+ return dev_seq_open_ops(inode, file, &dev_mc_seq_ops);
}
static const struct file_operations dev_mc_seq_fops = {
--
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