[34-longterm 070/260] kernel/groups.c: fix integer overflow in groups_search

Paul Gortmaker
2011-01-02T08:02:47Z

From: Jerome Marchand <jmarchan@redhat.com>

commit 1c24de60e50fb19b94d94225458da17c720f0729 upstream.

gid_t is a unsigned int. If group_info contains a gid greater than
MAX_INT, groups_search() function may look on the wrong side of the search
tree.

This solves some unfair "permission denied" problems.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
kernel/groups.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/groups.c b/kernel/groups.c
index 2b45b2e..f0c2528 100644
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -143,10 +143,9 @@ int groups_search(const struct group_info *group_info, gid_t grp)
right = group_info->ngroups;
while (left < right) {
unsigned int mid = (left+right)/2;
- int cmp = grp - GROUP_AT(group_info, mid);
- if (cmp > 0)
+ if (grp > GROUP_AT(group_info, mid))
left = mid + 1;
- else if (cmp < 0)
+ else if (grp < GROUP_AT(group_info, mid))
right = mid;
else
return 1;
--
1.7.3.3