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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id u8-v6sm15725493wrr.33.2018.11.13.07.18.36 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 13 Nov 2018 07:18:36 -0800 (PST) From: Ondrej Mosnacek To: selinux@vger.kernel.org, Paul Moore Cc: Qian Cai , Stephen Smalley , Eric Paris , linux-kernel@vger.kernel.org, Ondrej Mosnacek , stable@vger.kernel.org, Richard Haines Subject: [PATCH] selinux: check length properly in SCTP bind hook Date: Tue, 13 Nov 2018 16:16:08 +0100 Message-Id: <20181113151608.30424-1-omosnace@redhat.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <53491A18-DD21-4E34-BC2F-AB449C7844E8@gmx.us> References: <53491A18-DD21-4E34-BC2F-AB449C7844E8@gmx.us> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org selinux_sctp_bind_connect() must verify if the address buffer has sufficient length before accessing the 'sa_family' field. See __sctp_connect() for a similar check. The length of the whole address ('len') is already checked in the callees. Reported-by: Qian Cai Fixes: d452930fd3b9 ("selinux: Add SCTP support") Cc: # 4.17+ Cc: Richard Haines Signed-off-by: Ondrej Mosnacek --- Hi, On Mon, Nov 12, 2018 at 8:39 PM Qian Cai wrote: > Running the trinity fuzzer on the latest mainline (rc2) generates this, > > [15029.879626] BUG: KASAN: slab-out-of-bounds in selinux_sctp_bind_connect+0x60/0x150 > [15029.887275] Read of size 2 at addr ffff801ec53c5080 by task trinity-main/18081 > [15029.887294] > [15029.887304] CPU: 28 PID: 18081 Comm: trinity-main Tainted: G W OE 4.20.0-rc2+ #15 > [15029.887311] Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.50 06/01/2018 > [15000.084786] [15029.887320] Call trace: > [15029.915511] dump_backtrace+0x0/0x2c8 > [15029.920046] show_stack+0x24/0x30 > [15029.923367] dump_stack+0x118/0x19c > [15029.927539] print_address_description+0x68/0x2a0 > [15029.932245] kasan_report+0x1b4/0x348 > [15029.938760] __asan_load2+0x7c/0xa0 > [15029.945098] selinux_sctp_bind_connect+0x60/0x150 > > [15029.950571] security_sctp_bind_connect+0x58/0x90 > [15029.955493] __sctp_setsockopt_connectx+0x68/0x128 [sctp] > [15029.960943] sctp_setsockopt+0x764/0x2928 [sctp] > [15029.965564] sock_common_setsockopt+0x6c/0x80 > [15029.969923] __arm64_sys_setsockopt+0x13c/0x1f0 > [15029.974456] el0_svc_handler+0xd4/0x198 > [15029.978293] el0_svc+0x8/0xc > [15029.981174] > [15029.982667] Allocated by task 18081: > [15029.986245] kasan_kmalloc.part.1+0x40/0x108 > [15029.990517] kasan_kmalloc+0xb4/0xc8 > [15029.994094] __kmalloc_node+0x1c4/0x638 > [15029.997933] kvmalloc_node+0x98/0xa8 > [15030.001511] vmemdup_user+0x34/0x128 > [15030.005137] __sctp_setsockopt_connectx+0x44/0x128 [sctp] > [15030.010586] sctp_setsockopt+0x764/0x2928 [sctp] > [15030.015205] sock_common_setsockopt+0x6c/0x80 > [15030.019564] __arm64_sys_setsockopt+0x13c/0x1f0 > [15030.024096] el0_svc_handler+0xd4/0x198 > [15030.027933] el0_svc+0x8/0xc > [15030.030814] > [15030.032306] Freed by task 3025: > [15030.035451] __kasan_slab_free+0x114/0x228 > [15030.039548] kasan_slab_free+0x10/0x18 > [15030.043299] kfree+0x114/0x408 > [15030.046357] selinux_sk_free_security+0x38/0x48 > [15030.050888] security_sk_free+0x3c/0x58 > [15030.054727] __sk_destruct+0x3e8/0x570 > [15030.058478] sk_destruct+0x4c/0x58 > [15030.061881] __sk_free+0x68/0x138 > [15030.065197] sk_free+0x3c/0x48 > [15030.068255] unix_release_sock+0x4a8/0x550 > [15030.072353] unix_release+0x34/0x50 > [15030.075843] __sock_release+0x74/0x110 > [15030.079593] sock_close+0x24/0x38 > [15030.082913] __fput+0x1b8/0x368 > [15030.086055] ____fput+0x20/0x30 > [15030.089199] task_work_run+0x14c/0x1a8 > [15030.092951] do_notify_resume+0x1e4/0x200 > [15030.096961] work_pending+0x8/0x14 > [15030.100363] > [15030.101856] The buggy address belongs to the object at ffff801ec53c5080 > [15030.101856] which belongs to the cache kmalloc-128 of size 128 > [15030.114376] The buggy address is located 0 bytes inside of > [15030.114376] 128-byte region [ffff801ec53c5080, ffff801ec53c5100) > [15030.125939] The buggy address belongs to the page: > [15030.130732] page:ffff7fe007b14f00 count:1 mapcount:0 mapping:ffff8016c0010480 index:0x0 > [15030.138738] flags: 0x5fffff0000000200(slab) > [15030.142926] raw: 5fffff0000000200 ffff7fe007980608 ffff801ec000fd60 ffff8016c0010480 > [15030.150671] raw: 0000000000000000 0000000000660066 00000001ffffffff 0000000000000000 > [15030.158413] page dumped because: kasan: bad access detected > [15030.163984] > [15030.165476] Memory state around the buggy address: > [15030.170269] ffff801ec53c4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > [15030.177491] ffff801ec53c5000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > [15030.184714] >ffff801ec53c5080: 01 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > [15030.191934] ^ > [15030.195164] ffff801ec53c5100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > [15030.202386] ffff801ec53c5180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > [15030.209607] ================================================================== > [15030.216828] Disabling lock debugging due to kernel taint I think I found the cause - Qian, can you test this patch if it fixes the problem? security/selinux/hooks.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 7ce683259357..a67459eb62d5 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -5318,6 +5318,9 @@ static int selinux_sctp_bind_connect(struct sock *sk, int optname, addr_buf = address; while (walk_size < addrlen) { + if (walk_size + sizeof(sa_family_t) > addrlen) + return -EINVAL; + addr = addr_buf; switch (addr->sa_family) { case AF_UNSPEC: -- 2.17.2