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authorTejun Heo <tj@kernel.org>2010-02-22 12:44:19 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-02-22 19:50:34 -0800
commitd2e7276b6b5e4bc2148891a056d5862c5314342d (patch)
tree0013ab5f52d700dae771dcedf3f0f333486be5b6 /lib/idr.c
parent701188374b6f1ef9cf7e4dce4a2e69ef4c0012ac (diff)
downloadlinux-linaro-precise-d2e7276b6b5e4bc2148891a056d5862c5314342d.tar.gz
idr: fix a critical misallocation bug, take#2
This is retry of reverted 859ddf09743a8cc680af33f7259ccd0fd36bfe9d ("idr: fix a critical misallocation bug") which contained two bugs. * pa[idp->layers] should be cleared even if it's not used by sub_alloc() because it's used by mark idr_mark_full(). * The original condition check also assigned pa[l] to p which the new code didn't do thus leaving p pointing at the wrong layer. Both problems have been fixed and the idr code has received good amount testing using userland testing setup where simple bitmap allocator is run parallel to verify the result of idr allocation. The bug this patch fixes is caused by sub_alloc() optimization path bypassing out-of-room condition check and restarting allocation loop with starting value higher than maximum allowed value. For detailed description, please read commit message of 859ddf09. Signed-off-by: Tejun Heo <tj@kernel.org> Based-on-patch-from: Eric Paris <eparis@redhat.com> Reported-by: Eric Paris <eparis@redhat.com> Tested-by: Stefan Lippers-Hollmann <s.l-h@gmx.de> Tested-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/idr.c')
-rw-r--r--lib/idr.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/lib/idr.c b/lib/idr.c
index 1cac726c44b..0dc782216d4 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -156,10 +156,12 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
/* if already at the top layer, we need to grow */
- if (!(p = pa[l])) {
+ if (id >= 1 << (idp->layers * IDR_BITS)) {
*starting_id = id;
return IDR_NEED_TO_GROW;
}
+ p = pa[l];
+ BUG_ON(!p);
/* If we need to go up one layer, continue the
* loop; otherwise, restart from the top.