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authorJiri Slaby2016-10-21 14:13:24 +0200
committerDavid S. Miller2016-10-23 17:43:15 -0400
commita4b8e71b05c27bae6bad3bdecddbc6b68a3ad8cf (patch)
treefc68709b76295d038b512403a430522dcdb48f02 /net/sctp
parent235bde1ed3f0fff0f68f367ec8807b89ea151258 (diff)
net: sctp, forbid negative length
Most of getsockopt handlers in net/sctp/socket.c check len against sizeof some structure like: if (len < sizeof(int)) return -EINVAL; On the first look, the check seems to be correct. But since len is int and sizeof returns size_t, int gets promoted to unsigned size_t too. So the test returns false for negative lengths. Yes, (-1 < sizeof(long)) is false. Fix this in sctp by explicitly checking len < 0 before any getsockopt handler is called. Note that sctp_getsockopt_events already handled the negative case. Since we added the < 0 check elsewhere, this one can be removed. If not checked, this is the result: UBSAN: Undefined behaviour in ../mm/page_alloc.c:2722:19 shift exponent 52 is too large for 32-bit type 'int' CPU: 1 PID: 24535 Comm: syz-executor Not tainted 4.8.1-0-syzkaller #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.1-0-gb3ef39f-prebuilt.qemu-project.org 04/01/2014 0000000000000000 ffff88006d99f2a8 ffffffffb2f7bdea 0000000041b58ab3 ffffffffb4363c14 ffffffffb2f7bcde ffff88006d99f2d0 ffff88006d99f270 0000000000000000 0000000000000000 0000000000000034 ffffffffb5096422 Call Trace: [<ffffffffb3051498>] ? __ubsan_handle_shift_out_of_bounds+0x29c/0x300 ... [<ffffffffb273f0e4>] ? kmalloc_order+0x24/0x90 [<ffffffffb27416a4>] ? kmalloc_order_trace+0x24/0x220 [<ffffffffb2819a30>] ? __kmalloc+0x330/0x540 [<ffffffffc18c25f4>] ? sctp_getsockopt_local_addrs+0x174/0xca0 [sctp] [<ffffffffc18d2bcd>] ? sctp_getsockopt+0x10d/0x1b0 [sctp] [<ffffffffb37c1219>] ? sock_common_getsockopt+0xb9/0x150 [<ffffffffb37be2f5>] ? SyS_getsockopt+0x1a5/0x270 Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Vlad Yasevich <vyasevich@gmail.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: linux-sctp@vger.kernel.org Cc: netdev@vger.kernel.org Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sctp')
-rw-r--r--net/sctp/socket.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index fb02c7033307..9fbb6feb8c27 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4687,7 +4687,7 @@ static int sctp_getsockopt_disable_fragments(struct sock *sk, int len,
static int sctp_getsockopt_events(struct sock *sk, int len, char __user *optval,
int __user *optlen)
{
- if (len <= 0)
+ if (len == 0)
return -EINVAL;
if (len > sizeof(struct sctp_event_subscribe))
len = sizeof(struct sctp_event_subscribe);
@@ -6430,6 +6430,9 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname,
if (get_user(len, optlen))
return -EFAULT;
+ if (len < 0)
+ return -EINVAL;
+
lock_sock(sk);
switch (optname) {