Revision 979e0d74651ba5aa533277f2a6423d0f982fb6f6 authored by David Howells on 09 March 2014, 08:21:58 UTC, committed by Linus Torvalds on 10 March 2014, 01:57:18 UTC
This fixes CVE-2014-0102. The following command sequence produces an oops: keyctl new_session i=`keyctl newring _ses @s` keyctl link @s $i The problem is that search_nested_keyrings() sees two keyrings that have matching type and description, so keyring_compare_object() returns true. s_n_k() then passes the key to the iterator function - keyring_detect_cycle_iterator() - which *should* check to see whether this is the keyring of interest, not just one with the same name. Because assoc_array_find() will return one and only one match, I assumed that the iterator function would only see an exact match or never be called - but the iterator isn't only called from assoc_array_find()... The oops looks something like this: kernel BUG at /data/fs/linux-2.6-fscache/security/keys/keyring.c:1003! invalid opcode: 0000 [#1] SMP ... RIP: keyring_detect_cycle_iterator+0xe/0x1f ... Call Trace: search_nested_keyrings+0x76/0x2aa __key_link_check_live_key+0x50/0x5f key_link+0x4e/0x85 keyctl_keyring_link+0x60/0x81 SyS_keyctl+0x65/0xe4 tracesys+0xdd/0xe2 The fix is to make keyring_detect_cycle_iterator() check that the key it has is the key it was actually looking for rather than calling BUG_ON(). A testcase has been included in the keyutils testsuite for this: http://git.kernel.org/cgit/linux/kernel/git/dhowells/keyutils.git/commit/?id=891f3365d07f1996778ade0e3428f01878a1790b Reported-by: Tommi Rantala <tt.rantala@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <james.l.morris@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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hweight.c
#include <linux/export.h>
#include <linux/bitops.h>
#include <asm/types.h>
/**
* hweightN - returns the hamming weight of a N-bit word
* @x: the word to weigh
*
* The Hamming Weight of a number is the total number of bits set in it.
*/
unsigned int __sw_hweight32(unsigned int w)
{
#ifdef ARCH_HAS_FAST_MULTIPLIER
w -= (w >> 1) & 0x55555555;
w = (w & 0x33333333) + ((w >> 2) & 0x33333333);
w = (w + (w >> 4)) & 0x0f0f0f0f;
return (w * 0x01010101) >> 24;
#else
unsigned int res = w - ((w >> 1) & 0x55555555);
res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
res = (res + (res >> 4)) & 0x0F0F0F0F;
res = res + (res >> 8);
return (res + (res >> 16)) & 0x000000FF;
#endif
}
EXPORT_SYMBOL(__sw_hweight32);
unsigned int __sw_hweight16(unsigned int w)
{
unsigned int res = w - ((w >> 1) & 0x5555);
res = (res & 0x3333) + ((res >> 2) & 0x3333);
res = (res + (res >> 4)) & 0x0F0F;
return (res + (res >> 8)) & 0x00FF;
}
EXPORT_SYMBOL(__sw_hweight16);
unsigned int __sw_hweight8(unsigned int w)
{
unsigned int res = w - ((w >> 1) & 0x55);
res = (res & 0x33) + ((res >> 2) & 0x33);
return (res + (res >> 4)) & 0x0F;
}
EXPORT_SYMBOL(__sw_hweight8);
unsigned long __sw_hweight64(__u64 w)
{
#if BITS_PER_LONG == 32
return __sw_hweight32((unsigned int)(w >> 32)) +
__sw_hweight32((unsigned int)w);
#elif BITS_PER_LONG == 64
#ifdef ARCH_HAS_FAST_MULTIPLIER
w -= (w >> 1) & 0x5555555555555555ul;
w = (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);
w = (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;
return (w * 0x0101010101010101ul) >> 56;
#else
__u64 res = w - ((w >> 1) & 0x5555555555555555ul);
res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
res = res + (res >> 8);
res = res + (res >> 16);
return (res + (res >> 32)) & 0x00000000000000FFul;
#endif
#endif
}
EXPORT_SYMBOL(__sw_hweight64);
![swh spinner](/static/img/swh-spinner.gif)
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