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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hulk Robot <hulkci@huawei.com>,
        Wang Yufen <wangyufen@huawei.com>,
        Paul Moore <paul@paul-moore.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 108/285] netlabel: fix out-of-bounds memory accesses
Date:   Tue, 12 Apr 2022 08:29:25 +0200
Message-Id: <20220412062946.782236138@linuxfoundation.org>
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References: <20220412062943.670770901@linuxfoundation.org>
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From: Wang Yufen <wangyufen@huawei.com>

[ Upstream commit f22881de730ebd472e15bcc2c0d1d46e36a87b9c ]

In calipso_map_cat_ntoh(), in the for loop, if the return value of
netlbl_bitmap_walk() is equal to (net_clen_bits - 1), when
netlbl_bitmap_walk() is called next time, out-of-bounds memory accesses
of bitmap[byte_offset] occurs.

The bug was found during fuzzing. The following is the fuzzing report
 BUG: KASAN: slab-out-of-bounds in netlbl_bitmap_walk+0x3c/0xd0
 Read of size 1 at addr ffffff8107bf6f70 by task err_OH/252

 CPU: 7 PID: 252 Comm: err_OH Not tainted 5.17.0-rc7+ #17
 Hardware name: linux,dummy-virt (DT)
 Call trace:
  dump_backtrace+0x21c/0x230
  show_stack+0x1c/0x60
  dump_stack_lvl+0x64/0x7c
  print_address_description.constprop.0+0x70/0x2d0
  __kasan_report+0x158/0x16c
  kasan_report+0x74/0x120
  __asan_load1+0x80/0xa0
  netlbl_bitmap_walk+0x3c/0xd0
  calipso_opt_getattr+0x1a8/0x230
  calipso_sock_getattr+0x218/0x340
  calipso_sock_getattr+0x44/0x60
  netlbl_sock_getattr+0x44/0x80
  selinux_netlbl_socket_setsockopt+0x138/0x170
  selinux_socket_setsockopt+0x4c/0x60
  security_socket_setsockopt+0x4c/0x90
  __sys_setsockopt+0xbc/0x2b0
  __arm64_sys_setsockopt+0x6c/0x84
  invoke_syscall+0x64/0x190
  el0_svc_common.constprop.0+0x88/0x200
  do_el0_svc+0x88/0xa0
  el0_svc+0x128/0x1b0
  el0t_64_sync_handler+0x9c/0x120
  el0t_64_sync+0x16c/0x170

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/netlabel/netlabel_kapi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
index beb0e573266d..54c083003947 100644
--- a/net/netlabel/netlabel_kapi.c
+++ b/net/netlabel/netlabel_kapi.c
@@ -885,6 +885,8 @@ int netlbl_bitmap_walk(const unsigned char *bitmap, u32 bitmap_len,
 	unsigned char bitmask;
 	unsigned char byte;
 
+	if (offset >= bitmap_len)
+		return -1;
 	byte_offset = offset / 8;
 	byte = bitmap[byte_offset];
 	bit_spot = offset;
-- 
2.35.1