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Commit 1efa3c05 authored by Randy Dunlap's avatar Randy Dunlap Committed by David S. Miller
Browse files

[NET] compat ifconf: fix limits 



A recent change to compat. dev_ifconf() in fs/compat_ioctl.c
causes ifconf data to be truncated 1 entry too early when copying it
to userspace.  The correct amount of data (length) is returned,
but the final entry is empty (zero, not filled in).
The for-loop 'i' check should use <= to allow the final struct
ifreq32 to be copied.  I also used the ifconf-corruption program
in kernel bugzilla #4746 to make sure that this change does not
re-introduce the corruption.

Signed-off-by: default avatarRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2ec5e3a8

fs/compat_ioctl.c

+1 −1
Original line number Diff line number Diff line
@@ -446,7 +446,7 @@ static int dev_ifconf(unsigned int fd, unsigned int cmd, unsigned long arg) 
	ifr = ifc.ifc_req;

	ifr32 = compat_ptr(ifc32.ifcbuf);

	for (i = 0, j = 0;

             i + sizeof (struct ifreq32) < ifc32.ifc_len && j < ifc.ifc_len;

             i + sizeof (struct ifreq32) <= ifc32.ifc_len && j < ifc.ifc_len;

	     i += sizeof (struct ifreq32), j += sizeof (struct ifreq)) {

		if (copy_in_user(ifr32, ifr, sizeof (struct ifreq32)))

			return -EFAULT;