apparmor: fix off-by-one comparison on MAXMAPPED_SIG

This came in yesterday, and I have verified our regression tests
were missing this and it can cause an oops. Please apply.

There is a an off-by-one comparision on sig against MAXMAPPED_SIG
that can lead to a read outside the sig_map array if sig
is MAXMAPPED_SIG. Fix this.

Verified that the check is an out of bounds case that can cause an oops.

Revised: add comparison fix to second case
Fixes: cd1dbf76b23d ("apparmor: add the ability to mediate signals")
Signed-off-by: Colin Ian King <>
Signed-off-by: John Johansen <>
Signed-off-by: Linus Torvalds <>
diff --git a/security/apparmor/ipc.c b/security/apparmor/ipc.c
index 66fb9ed..7ca0032 100644
--- a/security/apparmor/ipc.c
+++ b/security/apparmor/ipc.c
@@ -128,7 +128,7 @@
 		return SIGUNKNOWN;
 	else if (sig >= SIGRTMIN)
 		return sig - SIGRTMIN + 128;	/* rt sigs mapped to 128 */
-	else if (sig <= MAXMAPPED_SIG)
+	else if (sig < MAXMAPPED_SIG)
 		return sig_map[sig];
 	return SIGUNKNOWN;
@@ -163,7 +163,7 @@
 			audit_signal_mask(ab, aad(sa)->denied);
-	if (aad(sa)->signal <= MAXMAPPED_SIG)
+	if (aad(sa)->signal < MAXMAPPED_SIG)
 		audit_log_format(ab, " signal=%s", sig_names[aad(sa)->signal]);
 		audit_log_format(ab, " signal=rtmin+%d",