[PATCH] Add linux-next specific files for 20220923

Hawkins Jiawei
2022-09-24T07:10:50Z

From: Stephen Rothwell <sfr@canb.auug.org.au>

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 483fed3b5dc8 Add linux-next specific files for 20220921
> git tree: linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1154ddd5080000
> kernel config: https://syzkaller.appspot.com/x/.config?x=849cb9f70f15b1ba
> dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157c196f080000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f12618880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/1cb3f4618323/disk-483fed3b.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/cc02cb30b495/vmlinux-483fed3b.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com
>
> ------------[ cut here ]------------
> memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4)
> WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623
> Modules linked in:
> CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022
> RIP: 0010:wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623
> Code: fa ff ff e8 cd b9 db f8 b9 04 00 00 00 4c 89 e6 48 c7 c2 e0 56 11 8b 48 c7 c7 20 56 11 8b c6 05 94 8e 2a 05 01 e8 b8 b0 a6 00 <0f> 0b e9 9b fa ff ff e8 6f ef 27 f9 e9 a6 fd ff ff e8 c5 ef 27 f9
> RSP: 0018:ffffc90003b2fbc0 EFLAGS: 00010286
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: ffff888021d157c0 RSI: ffffffff81620348 RDI: fffff52000765f6a
> RBP: ffff88801e15c780 R08: 0000000000000005 R09: 0000000000000000
> R10: 0000000080000000 R11: 20676e696e6e6170 R12: 0000000000000008
> R13: ffff888025a72640 R14: ffff8880225d402c R15: ffff8880225d4034
> FS: 0000555556bd9300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fbda677dfb8 CR3: 000000007b976000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022
> wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955
> wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline]
> wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline]
> wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049
> sock_ioctl+0x285/0x640 net/socket.c:1220
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:870 [inline]
> __se_sys_ioctl fs/ioctl.c:856 [inline]
> __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
> 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+0x63/0xcd
> RIP: 0033:0x7fbda6736af9
> Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffd45e80138 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbda6736af9
> RDX: 0000000020000000 RSI: 0000000000008b04 RDI: 0000000000000003
> RBP: 00007fbda66faca0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbda66fad30
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> </TASK>

I think this is the samiliar problem as what Kees Cook pointed out in
https://lore.kernel.org/linux-next/202209211250.3049C29@keescook/

It seems that memcpy() will performs run-time buffer bounds
checking, which triggers this warning.

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
master

diff --git a/include/linux/wireless.h b/include/linux/wireless.h
index 2d1b54556eff..81603848b0aa 100644
--- a/include/linux/wireless.h
+++ b/include/linux/wireless.h
@@ -26,7 +26,10 @@ struct compat_iw_point {
struct __compat_iw_event {
__u16 len; /* Real length of this stuff */
__u16 cmd; /* Wireless IOCTL */
- compat_caddr_t pointer;
+ union {
+ compat_caddr_t pointer;
+ __DECLARE_FLEX_ARRAY(__u8, pointer_flex);
+ };
};
#define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer)
#define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length)
diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c
index 76a80a41615b..9d0b50abbe09 100644
--- a/net/wireless/wext-core.c
+++ b/net/wireless/wext-core.c
@@ -620,7 +620,7 @@ void wireless_send_event(struct net_device * dev,
extra, extra_len);
} else {
/* extra_len must be zero, so no if (extra) needed */
- memcpy(&compat_event->pointer, wrqu,
+ memcpy(&compat_event->pointer_flex, wrqu,
hdr_len - IW_EV_COMPAT_LCP_LEN);
}