Subject: [merged] idr-fix-overflow-bug-during-maximum-id-calculation-at-maximum-height.patch removed from -mm tree To: laijs@xxxxxxxxxxxxxx,stable@xxxxxxxxxxxxxxx,tj@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Mon, 09 Jun 2014 12:34:57 -0700 The patch titled Subject: idr: fix overflow bug during maximum ID calculation at maximum height has been removed from the -mm tree. Its filename was idr-fix-overflow-bug-during-maximum-id-calculation-at-maximum-height.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Lai Jiangshan <laijs@xxxxxxxxxxxxxx> Subject: idr: fix overflow bug during maximum ID calculation at maximum height 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@xxxxxxxxxx: Updated patch description.] Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/idr.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff -puN lib/idr.c~idr-fix-overflow-bug-during-maximum-id-calculation-at-maximum-height lib/idr.c --- a/lib/idr.c~idr-fix-overflow-bug-during-maximum-id-calculation-at-maximum-height +++ a/lib/idr.c @@ -249,7 +249,7 @@ static int sub_alloc(struct idr *idp, in id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1; /* if already at the top layer, we need to grow */ - if (id >= 1 << (idp->layers * IDR_BITS)) { + if (id > idr_max(idp->layers)) { *starting_id = id; return -EAGAIN; } @@ -811,12 +811,10 @@ void *idr_replace(struct idr *idp, void if (!p) return ERR_PTR(-EINVAL); - n = (p->layer+1) * IDR_BITS; - - if (id >= (1 << n)) + if (id > idr_max(p->layer + 1)) return ERR_PTR(-EINVAL); - n -= IDR_BITS; + n = p->layer * IDR_BITS; while ((n > 0) && p) { p = p->ary[(id >> n) & IDR_MASK]; n -= IDR_BITS; _ Patches currently in -mm which might be from laijs@xxxxxxxxxxxxxx are origin.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html