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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: Chris Salls <salls@cs.ucsb.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Chris Salls 2017-04-07 23:48:11 -07:00 committed by Linus Torvalds
parent 425fffd886
commit cf01fb9985
1 changed files with 8 additions and 12 deletions
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24
mm/mempolicy.c
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@ -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);
nm = compat_alloc_user_space(alloc_size);
err |= copy_to_user(nm, bm, alloc_size);
}
if (err)
if (compat_get_bitmap(bm, nmask, nr_bits))
return -EFAULT;
nm = compat_alloc_user_space(alloc_size);
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);
nm = compat_alloc_user_space(alloc_size);
err |= copy_to_user(nm, nodes_addr(bm), alloc_size);
}
if (err)
if (compat_get_bitmap(nodes_addr(bm), nmask, nr_bits))
return -EFAULT;
nm = compat_alloc_user_space(alloc_size);
if (copy_to_user(nm, nodes_addr(bm), alloc_size))
return -EFAULT;
}
return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
}