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Commit cf01fb99 authored by Chris Salls's avatar Chris Salls Committed by Linus Torvalds
Browse files

mm/mempolicy.c: fix error handling in set_mempolicy and mbind. 



In the case that compat_get_bitmap fails we do not want to copy the
bitmap to the user as it will contain uninitialized stack data and leak
sensitive data.

Signed-off-by: default avatarChris Salls <salls@cs.ucsb.edu>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 425fffd8

mm/mempolicy.c

+8 −12
Original line number Diff line number Diff line
@@ -1529,7 +1529,6 @@ COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy, 
COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,

		       compat_ulong_t, maxnode)

{

	long err = 0;

	unsigned long __user *nm = NULL;

	unsigned long nr_bits, alloc_size;

	DECLARE_BITMAP(bm, MAX_NUMNODES);
@@ -1538,13 +1537,12 @@ COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask, 
	alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;



	if (nmask) {

		err = compat_get_bitmap(bm, nmask, nr_bits);

		if (compat_get_bitmap(bm, nmask, nr_bits))

			return -EFAULT;

		nm = compat_alloc_user_space(alloc_size);

		err |= copy_to_user(nm, bm, alloc_size);

	}



	if (err)

		if (copy_to_user(nm, bm, alloc_size))

			return -EFAULT;

	}



	return sys_set_mempolicy(mode, nm, nr_bits+1);

}
@@ -1553,7 +1551,6 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len, 
		       compat_ulong_t, mode, compat_ulong_t __user *, nmask,

		       compat_ulong_t, maxnode, compat_ulong_t, flags)

{

	long err = 0;

	unsigned long __user *nm = NULL;

	unsigned long nr_bits, alloc_size;

	nodemask_t bm;
@@ -1562,13 +1559,12 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len, 
	alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;



	if (nmask) {

		err = compat_get_bitmap(nodes_addr(bm), nmask, nr_bits);

		if (compat_get_bitmap(nodes_addr(bm), nmask, nr_bits))

			return -EFAULT;

		nm = compat_alloc_user_space(alloc_size);

		err |= copy_to_user(nm, nodes_addr(bm), alloc_size);

	}



	if (err)

		if (copy_to_user(nm, nodes_addr(bm), alloc_size))

			return -EFAULT;

	}



	return sys_mbind(start, len, mode, nm, nr_bits+1, flags);

}