In SOL_PACKET, we can sanitize the setsockopt() syscall a bit in the
following ways:
i) PACKET_VERSION is always checked in the kernel and it is quite
likely to return -EINVAL here, very unlikely to crash this option.
However, if we pass the correct values to it (TPACKET_V1, TPACKET_V2,
TPACKET_V3), we can jump into this version specific code on other
syscalls on that socket.
ii) PACKET_{R,T}X_RING never gets a structure of size int, so it might
always return -EINVAL here. Depending on the TPACKET version, it
can either be tpacket_req or tpacket_req3. Make it more likely to
have size tpacket_req though.
Signed-off-by: Daniel Borkmann <[email protected]>
---
syscalls/setsockopt.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/syscalls/setsockopt.c b/syscalls/setsockopt.c
index ce610af..2932bfb 100644
--- a/syscalls/setsockopt.c
+++ b/syscalls/setsockopt.c
@@ -185,6 +185,22 @@ void sanitise_setsockopt(int childno)
case SOL_PACKET:
val = rand() % NR_SOL_PACKET_OPTS;
shm->a3[childno] = packet_opts[val];
+
+ /* Adjust length according to operation set. */
+ switch (shm->a3[childno]) {
+ case PACKET_VERSION:
+ page_rand[0] = rand() % 3; /* tpacket versions 1/2/3 */
+ break;
+ case PACKET_TX_RING:
+ case PACKET_RX_RING:
+ if (rand() % 3 == 0)
+ shm->a5[childno] = sizeof(struct tpacket_req3);
+ else
+ shm->a5[childno] = sizeof(struct tpacket_req);
+ break;
+ default:
+ break;
+ }
break;
case SOL_ATM:
--
1.7.11.7
--
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