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authorCyrill Gorcunov <gorcunov@gmail.com>2008-08-31 19:25:49 +0400
committerJ. Bruce Fields <bfields@citi.umich.edu>2008-09-01 14:24:24 -0400
commit27df6f25ff218072e0e879a96beeb398a79cdbc8 (patch)
tree92156018e74a963b2abb94bd51a7e7d6b6a72f34
parentc228c24bf1138d4757dbe20615df655815446da3 (diff)
sunrpc: fix possible overrun on read of /proc/sys/sunrpc/transports
Vegard Nossum reported ---------------------- > I noticed that something weird is going on with /proc/sys/sunrpc/transports. > This file is generated in net/sunrpc/sysctl.c, function proc_do_xprt(). When > I "cat" this file, I get the expected output: > $ cat /proc/sys/sunrpc/transports > tcp 1048576 > udp 32768 > But I think that it does not check the length of the buffer supplied by > userspace to read(). With my original program, I found that the stack was > being overwritten by the characters above, even when the length given to > read() was just 1. David Wagner added (among other things) that copy_to_user could be probably used here. Ingo Oeser suggested to use simple_read_from_buffer() here. The conclusion is that proc_do_xprt doesn't check for userside buffer size indeed so fix this by using Ingo's suggestion. Reported-by: Vegard Nossum <vegard.nossum@gmail.com> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> CC: Ingo Oeser <ioe-lkml@rameria.de> Cc: Neil Brown <neilb@suse.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Greg Banks <gnb@sgi.com> Cc: Tom Tucker <tom@opengridcomputing.com> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
-rw-r--r--net/sunrpc/sysctl.c18
1 files changed, 4 insertions, 14 deletions
diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index 0f8c439b848..5231f7aaac0 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -60,24 +60,14 @@ static int proc_do_xprt(ctl_table *table, int write, struct file *file,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
char tmpbuf[256];
- int len;
+ size_t len;
+
if ((*ppos && !write) || !*lenp) {
*lenp = 0;
return 0;
}
- if (write)
- return -EINVAL;
- else {
- len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
- if (!access_ok(VERIFY_WRITE, buffer, len))
- return -EFAULT;
-
- if (__copy_to_user(buffer, tmpbuf, len))
- return -EFAULT;
- }
- *lenp -= len;
- *ppos += len;
- return 0;
+ len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
+ return simple_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
}
static int