apparmor: increase left match history buffer size

There have been cases reported where a history buffer size of 8 was
not enough to resolve conflict overlaps. Increase the buffer to and
get rid of the size element which is currently just storing the
constant WB_HISTORY_SIZE.

Signed-off-by: John Johansen <john.johansen@canonical.com>

diff --git a/security/apparmor/include/match.h b/security/apparmor/include/match.h
index 958d2b5..90fc050 100644 (file)
--- a/security/apparmor/include/match.h
+++ b/security/apparmor/include/match.h
@@ -138,7 +138,7 @@ unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start,
 
 void aa_dfa_free_kref(struct kref *kref);
 
-#define WB_HISTORY_SIZE 8
+#define WB_HISTORY_SIZE 24
 struct match_workbuf {
        unsigned int count;
        unsigned int pos;
@@ -151,7 +151,6 @@ struct match_workbuf N = {          \
        .count = 0,                     \
        .pos = 0,                       \
        .len = 0,                       \
-       .size = WB_HISTORY_SIZE,                        \
 }
 
 unsigned int aa_dfa_leftmatch(struct aa_dfa *dfa, unsigned int start,

diff --git a/security/apparmor/match.c b/security/apparmor/match.c
index 55f2ee5..21fad8f 100644 (file)
--- a/security/apparmor/match.c
+++ b/security/apparmor/match.c
@@ -620,8 +620,8 @@ unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start,
 
 #define inc_wb_pos(wb)                                         \
 do {                                                           \
-       wb->pos = (wb->pos + 1) & (wb->size - 1);               \
-       wb->len = (wb->len + 1) & (wb->size - 1);               \
+       wb->pos = (wb->pos + 1) & (WB_HISTORY_SIZE - 1);                \
+       wb->len = (wb->len + 1) & (WB_HISTORY_SIZE - 1);                \
 } while (0)
 
 /* For DFAs that don't support extended tagging of states */
@@ -640,7 +640,7 @@ static bool is_loop(struct match_workbuf *wb, unsigned int state,
                        return true;
                }
                if (pos == 0)
-                       pos = wb->size;
+                       pos = WB_HISTORY_SIZE;
                pos--;
        }