linux-kernel - Re: [PATCH] net/socket: the length value of the input socket option parameter is too small

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Message-ID: <32f25edc-4b4e-49b8-a9a4-50ed9da258bf@gmail.com>
Date: Fri, 5 Apr 2024 13:39:02 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: Edward Adam Davis <eadavis@...com>,
 syzbot+d4ecae01a53fd9b42e7d@...kaller.appspotmail.com
Cc: johan.hedberg@...il.com, linux-bluetooth@...r.kernel.org,
 linux-kernel@...r.kernel.org, luiz.dentz@...il.com, marcel@...tmann.org,
 syzkaller-bugs@...glegroups.com, edumazet@...gle.com
Subject: Re: [PATCH] net/socket: the length value of the input socket option
 parameter is too small


On 4/5/24 12:16, Edward Adam Davis wrote:
> [Syzbot reported]
> BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
> BUG: KASAN: slab-out-of-bounds in copy_from_sockptr include/linux/sockptr.h:55 [inline]
> BUG: KASAN: slab-out-of-bounds in rfcomm_sock_setsockopt_old net/bluetooth/rfcomm/sock.c:632 [inline]
> BUG: KASAN: slab-out-of-bounds in rfcomm_sock_setsockopt+0x893/0xa70 net/bluetooth/rfcomm/sock.c:673
> Read of size 4 at addr ffff8880209a8bc3 by task syz-executor632/5064
>
> CPU: 0 PID: 5064 Comm: syz-executor632 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Call Trace:
>   <TASK>
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>   print_address_description mm/kasan/report.c:377 [inline]
>   print_report+0x169/0x550 mm/kasan/report.c:488
>   kasan_report+0x143/0x180 mm/kasan/report.c:601
>   copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
>   copy_from_sockptr include/linux/sockptr.h:55 [inline]
>   rfcomm_sock_setsockopt_old net/bluetooth/rfcomm/sock.c:632 [inline]
>   rfcomm_sock_setsockopt+0x893/0xa70 net/bluetooth/rfcomm/sock.c:673
>   do_sock_setsockopt+0x3af/0x720 net/socket.c:2311
>   __sys_setsockopt+0x1ae/0x250 net/socket.c:2334
>   __do_sys_setsockopt net/socket.c:2343 [inline]
>   __se_sys_setsockopt net/socket.c:2340 [inline]
>   __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340
>   do_syscall_64+0xfb/0x240
>   entry_SYSCALL_64_after_hwframe+0x6d/0x75
> RIP: 0033:0x7f36ff898dc9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffe010c2208 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f36ff898dc9
> RDX: 0000000000000003 RSI: 0000000000000012 RDI: 0000000000000006
> RBP: 0000000000000006 R08: 0000000000000002 R09: 0000000000000000
> R10: 00000000200000c0 R11: 0000000000000246 R12: 0000555567399338
> R13: 000000000000000e R14: 0000000000000000 R15: 0000000000000000
>   </TASK>
>
> Allocated by task 5064:
>   kasan_save_stack mm/kasan/common.c:47 [inline]
>   kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
>   poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
>   __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
>   kasan_kmalloc include/linux/kasan.h:211 [inline]
>   __do_kmalloc_node mm/slub.c:3966 [inline]
>   __kmalloc+0x233/0x4a0 mm/slub.c:3979
>   kmalloc include/linux/slab.h:632 [inline]
>   __cgroup_bpf_run_filter_setsockopt+0xd2f/0x1040 kernel/bpf/cgroup.c:1869
>   do_sock_setsockopt+0x6b4/0x720 net/socket.c:2293
>   __sys_setsockopt+0x1ae/0x250 net/socket.c:2334
>   __do_sys_setsockopt net/socket.c:2343 [inline]
>   __se_sys_setsockopt net/socket.c:2340 [inline]
>   __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340
>   do_syscall_64+0xfb/0x240
>   entry_SYSCALL_64_after_hwframe+0x6d/0x75
>
> The buggy address belongs to the object at ffff8880209a8bc0
>   which belongs to the cache kmalloc-8 of size 8
> The buggy address is located 1 bytes to the right of
>   allocated 2-byte region [ffff8880209a8bc0, ffff8880209a8bc2)
> [Fix]
> The optlen value passed by syzbot to _sys_setsockopt() is 2, which results in
> only 2 bytes being allocated when allocating memory to kernel_optval, and the
> optval size passed when calling the function copy_from_sockptr() is 4 bytes.
> Here, optlen is determined uniformly in the entry function __sys_setsockopt().
> If its value is less than 4, the parameter is considered invalid.
>
> Reported-by: syzbot+d4ecae01a53fd9b42e7d@...kaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@...com>
> ---
>   net/socket.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/net/socket.c b/net/socket.c
> index e5f3af49a8b6..ac8fd4f6ebfe 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -2327,6 +2327,9 @@ int __sys_setsockopt(int fd, int level, int optname, char __user *user_optval,
>   	int err, fput_needed;
>   	struct socket *sock;
>   
> +	if (optlen < sizeof(int))
> +		return -EINVAL;
> +


Please cc netdev@ for core networking patches.

This patch is not good, please fix net/bluetooth/rfcomm/sock.c instead

I think I did this yesterday already :

https://lore.kernel.org/netdev/20240404124723.2429464-1-edumazet@google.com/T/


>   	sock = sockfd_lookup_light(fd, &err, &fput_needed);
>   	if (!sock)
>   		return err;