[CRIU] [Patch] Fix UB in choose_service_fd_base due to calling __builtin_clz(0)

[Radoslaw Burny]

From: Radoslaw Burny <rburny at google.com>

Subject: [PATCH] Fix UB in choose_service_fd_base.

Signed-off-by: Radoslaw Burny <rburny at google.com>

---
 criu/util.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/criu/util.c b/criu/util.c
index b19bf517..48ba09a8 100644
--- a/criu/util.c
+++ b/criu/util.c
@@ -588,9 +588,9 @@ static int choose_service_fd_base(struct pstree_item
*me)
        nr += 16; /* Safety pad */
        real_nr = nr;

-       nr /= (1024 / sizeof(void *));
+       /* Align nr to the power of 2 for easier debugging */
+       BUG_ON(nr <= 0);
        nr = 1 << (32 - __builtin_clz(nr));
-       nr *= (1024 / sizeof(void *));

        if (nr > service_fd_rlim_cur) {
                /* Right border is bigger, than rlim. OK, then just aligned
value is enough */
-- 
2.17.0.484.g0c8726318c-goog
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