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authorJohn Johansen <john.johansen@canonical.com>2012-02-22 00:32:30 -0800
committerJohn Johansen <john.johansen@canonical.com>2012-02-27 11:38:21 -0800
commit8b964eae204d791421677ec56b94a7b18cf8740d (patch)
tree7c1a7b5b6be9f2d9b60d8cba1094635d3f74466c /security/apparmor
parentade3ddc01e2e426cc24c744be85dcaad4e8f8aba (diff)
downloadlinux-8b964eae204d791421677ec56b94a7b18cf8740d.tar.gz
AppArmor: Fix underflow in xindex calculation
If the xindex value stored in the accept tables is 0, the extraction of that value will result in an underflow (0 - 4). In properly compiled policy this should not happen for file rules but it may be possible for other rule types in the future. To exploit this underflow a user would have to be able to load a corrupt policy, which requires CAP_MAC_ADMIN, overwrite system policy in kernel memory or know of a compiler error resulting in the flaw being present for loaded policy (no such flaw is known at this time). Signed-off-by: John Johansen <john.johansen@canonical.com> Acked-by: Kees Cook <kees@ubuntu.com>
Diffstat (limited to 'security/apparmor')
-rw-r--r--security/apparmor/include/file.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/security/apparmor/include/file.h b/security/apparmor/include/file.h
index ab8c6d87f75..f98fd4701d8 100644
--- a/security/apparmor/include/file.h
+++ b/security/apparmor/include/file.h
@@ -117,7 +117,7 @@ static inline u16 dfa_map_xindex(u16 mask)
index |= AA_X_NAME;
} else if (old_index == 3) {
index |= AA_X_NAME | AA_X_CHILD;
- } else {
+ } else if (old_index) {
index |= AA_X_TABLE;
index |= old_index - 4;
}