UBSan: Avoid dependency on undefined behavior in internal AES operation

The rcons[] and Td4s[] array values need to be type cast explicitly to
u32 for the left shift 24 operation to be defined due to the implicit
conversion to int not handling the case where MSB would become 1 without
depending on UB.

Credit to OSS-Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14929
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

diff --git a/src/crypto/aes_i.h b/src/crypto/aes_i.h
index 54375cf355837051c17f792828b1d7ba3f148418..b20ec92203ade84b21b01139c3d14798b22f374d 100644 (file)
--- a/src/crypto/aes_i.h
+++ b/src/crypto/aes_i.h
@@ -65,7 +65,7 @@ extern const u8 rcons[10];
 
 #else /* AES_SMALL_TABLES */
 
-#define RCON(i) (rcons[(i)] << 24)
+#define RCON(i) ((u32) rcons[(i)] << 24)
 
 static inline u32 rotr(u32 val, int bits)
 {
@@ -94,10 +94,10 @@ static inline u32 rotr(u32 val, int bits)
 #define TD1(i) rotr(Td0[((i) >> 16) & 0xff], 8)
 #define TD2(i) rotr(Td0[((i) >> 8) & 0xff], 16)
 #define TD3(i) rotr(Td0[(i) & 0xff], 24)
-#define TD41(i) (Td4s[((i) >> 24) & 0xff] << 24)
-#define TD42(i) (Td4s[((i) >> 16) & 0xff] << 16)
-#define TD43(i) (Td4s[((i) >> 8) & 0xff] << 8)
-#define TD44(i) (Td4s[(i) & 0xff])
+#define TD41(i) ((u32) Td4s[((i) >> 24) & 0xff] << 24)
+#define TD42(i) ((u32) Td4s[((i) >> 16) & 0xff] << 16)
+#define TD43(i) ((u32) Td4s[((i) >> 8) & 0xff] << 8)
+#define TD44(i) ((u32) Td4s[(i) & 0xff])
 #define TD0_(i) Td0[(i) & 0xff]
 #define TD1_(i) rotr(Td0[(i) & 0xff], 8)
 #define TD2_(i) rotr(Td0[(i) & 0xff], 16)