diff options
author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2014-06-06 14:37:10 -0700 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-06-30 20:11:54 -0700 |
commit | 7c50a27b68f395fee0c45cb769b4c8546dcac7a4 (patch) | |
tree | 94c94c7009968a353caf55aa7e7891385cc3f9b7 /fs/binfmt_script.c | |
parent | ffd6802830d5909dee42c4d786e420288a43815d (diff) |
idr: fix overflow bug during maximum ID calculation at maximum height
commit 3afb69cb5572b3c8c898c00880803cf1a49852c4 upstream.
idr_replace() open-codes the logic to calculate the maximum valid ID
given the height of the idr tree; unfortunately, the open-coded logic
doesn't account for the fact that the top layer may have unused slots
and over-shifts the limit to zero when the tree is at its maximum
height.
The following test code shows it fails to replace the value for
id=((1<<27)+42):
static void test5(void)
{
int id;
DEFINE_IDR(test_idr);
#define TEST5_START ((1<<27)+42) /* use the highest layer */
printk(KERN_INFO "Start test5\n");
id = idr_alloc(&test_idr, (void *)1, TEST5_START, 0, GFP_KERNEL);
BUG_ON(id != TEST5_START);
TEST_BUG_ON(idr_replace(&test_idr, (void *)2, TEST5_START) != (void *)1);
idr_destroy(&test_idr);
printk(KERN_INFO "End of test5\n");
}
Fix the bug by using idr_max() which correctly takes into account the
maximum allowed shift.
sub_alloc() shares the same problem and may incorrectly fail with
-EAGAIN; however, this bug doesn't affect correct operation because
idr_get_empty_slot(), which already uses idr_max(), retries with the
increased @id in such cases.
[tj@kernel.org: Updated patch description.]
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/binfmt_script.c')
0 files changed, 0 insertions, 0 deletions