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xen-netback: fix debugfs write length check

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Enlarge buffer size and check input length properly, so that we don't
misuse -ENOSPC.

Note that command like "kickXXXX" is still allowed, that's one patch for
another day if we really want to be very strict on this.

Reported-by: SeeChen Ng <seechen81@gmail.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: Zoltan Kiss <zoltan.kiss@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wei Liu 2014-08-12 11:59:29 +01:00 committed by David S. Miller
parent 490cc7d03c
commit 5c807005fa
1 changed files with 6 additions and 3 deletions
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9
drivers/net/xen-netback/xenbus.c
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@ -116,6 +116,7 @@ static int xenvif_read_io_ring(struct seq_file *m, void *v)
}
#define XENVIF_KICK_STR "kick"
#define BUFFER_SIZE 32
static ssize_t
xenvif_write_io_ring(struct file *filp, const char __user *buf, size_t count,
@ -124,22 +125,24 @@ xenvif_write_io_ring(struct file *filp, const char __user *buf, size_t count,
struct xenvif_queue *queue =
((struct seq_file *)filp->private_data)->private;
int len;
char write[sizeof(XENVIF_KICK_STR)];
char write[BUFFER_SIZE];
/* don't allow partial writes and check the length */
if (*ppos != 0)
return 0;
if (count < sizeof(XENVIF_KICK_STR) - 1)
if (count >= sizeof(write))
return -ENOSPC;
len = simple_write_to_buffer(write,
sizeof(write),
sizeof(write) - 1,
ppos,
buf,
count);
if (len < 0)
return len;
write[len] = '\0';
if (!strncmp(write, XENVIF_KICK_STR, sizeof(XENVIF_KICK_STR) - 1))
xenvif_interrupt(0, (void *)queue);
else {