Le lundi 28 novembre 2011 à 18:14 +1100, Anton Blanchard a écrit :
> 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@xxxxxxxxx>
> ---
>
> 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 = {
Good catch, thanks !
Problem added by commit f04565ddf52e4 (dev: use name hash for
dev_seq_ops)
Acked-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
CC: Mihai Maruseac <mihai.maruseac@xxxxxxxxx>
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