Re: [PATCH net-next] netlabel: fix out-of-bounds memory accesses
From: Paul Moore <paul@paul-moore.com>
Date: 2022-03-20 21:55:29
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On Fri, Mar 18, 2022 at 2:17 AM Wang Yufen [off-list ref] wrote:
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 <redacted> Signed-off-by: Wang Yufen <redacted> --- net/netlabel/netlabel_kapi.c | 2 ++ 1 file changed, 2 insertions(+)
Looks good to me, thanks for catching this and submitting a fix. Acked-by: Paul Moore <paul@paul-moore.com>
quoted hunk ↗ jump to hunk
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;
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