[PATCH 5.16 108/285] netlabel: fix out-of-bounds memory accesses

Greg Kroah-Hartman
2022-04-12T07:45:56Z

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