This is a note to let you know that I've just added the patch titled llc: fix out-of-bound array index in llc_sk_dev_hash() to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: llc-fix-out-of-bound-array-index-in-llc_sk_dev_hash.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 678bd5a53f6b2bf4051f489157fdce000b28c49f Author: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Fri Nov 5 14:42:14 2021 -0700 llc: fix out-of-bound array index in llc_sk_dev_hash() [ Upstream commit 8ac9dfd58b138f7e82098a4e0a0d46858b12215b ] Both ifindex and LLC_SK_DEV_HASH_ENTRIES are signed. This means that (ifindex % LLC_SK_DEV_HASH_ENTRIES) is negative if @ifindex is negative. We could simply make LLC_SK_DEV_HASH_ENTRIES unsigned. In this patch I chose to use hash_32() to get more entropy from @ifindex, like llc_sk_laddr_hashfn(). UBSAN: array-index-out-of-bounds in ./include/net/llc.h:75:26 index -43 is out of range for type 'hlist_head [64]' CPU: 1 PID: 20999 Comm: syz-executor.3 Not tainted 5.15.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 ubsan_epilogue+0xb/0x5a lib/ubsan.c:151 __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:291 llc_sk_dev_hash include/net/llc.h:75 [inline] llc_sap_add_socket+0x49c/0x520 net/llc/llc_conn.c:697 llc_ui_bind+0x680/0xd70 net/llc/af_llc.c:404 __sys_bind+0x1e9/0x250 net/socket.c:1693 __do_sys_bind net/socket.c:1704 [inline] __se_sys_bind net/socket.c:1702 [inline] __x64_sys_bind+0x6f/0xb0 net/socket.c:1702 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fa503407ae9 Fixes: 6d2e3ea28446 ("llc: use a device based hash table to speed up multicast delivery") Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/include/net/llc.h b/include/net/llc.h index df282d9b40170..9c10b121b49b0 100644 --- a/include/net/llc.h +++ b/include/net/llc.h @@ -72,7 +72,9 @@ struct llc_sap { static inline struct hlist_head *llc_sk_dev_hash(struct llc_sap *sap, int ifindex) { - return &sap->sk_dev_hash[ifindex % LLC_SK_DEV_HASH_ENTRIES]; + u32 bucket = hash_32(ifindex, LLC_SK_DEV_HASH_BITS); + + return &sap->sk_dev_hash[bucket]; } static inline