From: Stephen Hemminger <shemminger@linux-foundation.org>
To: netdev@vger.kernel.org
Subject: Fw: [Bug 10371] New: On big-endian machines getsockopt returns 0 (via optval) for optlen==1 when returned value should 255
Date: Mon, 31 Mar 2008 08:45:22 -0700 [thread overview]
Message-ID: <20080331084522.5c9a2732@extreme> (raw)
Begin forwarded message:
Date: Mon, 31 Mar 2008 08:16:05 -0700 (PDT)
From: bugme-daemon@bugzilla.kernel.org
To: shemminger@linux-foundation.org
Subject: [Bug 10371] New: On big-endian machines getsockopt returns 0 (via optval) for optlen==1 when returned value should 255
http://bugzilla.kernel.org/show_bug.cgi?id=10371
Summary: On big-endian machines getsockopt returns 0 (via optval)
for optlen==1 when returned value should 255
Product: Networking
Version: 2.5
KernelVersion: 2.6.24
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: IPV4
AssignedTo: shemminger@linux-foundation.org
ReportedBy: M.Piechaczek@osmosys.tv
Latest working kernel version:
Earliest failing kernel version: all 2.6
Distribution:
Hardware Environment:
Software Environment:
Problem Description:
On big-endian machines getsockopt fails for optlen==1 when returned value is
255.
Eg. after calling
unsigned char ttl = 255;
socklen_t len = sizeof(ttl);
setsockopt(socket, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, &len);
the following call will fail:
getsockopt(socket, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, &len);
"ttl" returned will be 0.
It's because of bug in /net/ipv4/ip_sockglue.c:
static int do_ip_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen)
....
if (len < sizeof(int) && len > 0 && val>=0 && val<255) {
unsigned char ucval = (unsigned char)val;
len = 1;
if (put_user(len, optlen))
return -EFAULT;
if (copy_to_user(optval,&ucval,1))
return -EFAULT;
} else {
len = min_t(unsigned int, sizeof(int), len);
if (put_user(len, optlen))
return -EFAULT;
if (copy_to_user(optval,&val,len))
return -EFAULT;
}
return 0;
}
The comparision in if-statement should be:
if (len < sizeof(int) && len > 0 && val>=0 && val<=255)
Otherwise on big-endian machines copy_to_user(optval,&val,len) routine copies
first (highest) byte which is 0 in that case.
This bug does not occur on low-endian machines since
copy_to_user(optval,&val,len) copies right (lowest) byte in that case.
--
Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.
reply other threads:[~2008-03-31 15:45 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20080331084522.5c9a2732@extreme \
--to=shemminger@linux-foundation.org \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox