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author | Hawkins Jiawei <yin31149@gmail.com> | 2022-09-27 07:34:59 +0800 |
---|---|---|
committer | Johannes Berg <johannes.berg@intel.com> | 2022-10-07 15:00:25 +0200 |
commit | e3e6e1d16a4cf7b63159ec71774e822194071954 (patch) | |
tree | 8d5aae546ff674d602fd17730828d5b4c4f30c9f /net | |
parent | d9e249704084982ac7581a560ffa284e11621d43 (diff) | |
download | linux-stable-e3e6e1d16a4cf7b63159ec71774e822194071954.tar.gz linux-stable-e3e6e1d16a4cf7b63159ec71774e822194071954.tar.bz2 linux-stable-e3e6e1d16a4cf7b63159ec71774e822194071954.zip |
wifi: wext: use flex array destination for memcpy()
Syzkaller reports buffer overflow false positive as follows:
------------[ 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
[...]
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
[...]
</TASK>
Wireless events will be sent on the appropriate channels in
wireless_send_event(). Different wireless events may have different
payload structure and size, so kernel uses **len** and **cmd** field
in struct __compat_iw_event as wireless event common LCP part, uses
**pointer** as a label to mark the position of remaining different part.
Yet the problem is that, **pointer** is a compat_caddr_t type, which may
be smaller than the relative structure at the same position. So during
wireless_send_event() tries to parse the wireless events payload, it may
trigger the memcpy() run-time destination buffer bounds checking when the
relative structure's data is copied to the position marked by **pointer**.
This patch solves it by introducing flexible-array field **ptr_bytes**,
to mark the position of the wireless events remaining part next to
LCP part. What's more, this patch also adds **ptr_len** variable in
wireless_send_event() to improve its maintainability.
Reported-and-tested-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/00000000000070db2005e95a5984@google.com/
Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net')
-rw-r--r-- | net/wireless/wext-core.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index 76a80a41615b..fe8765c4075d 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -468,6 +468,7 @@ void wireless_send_event(struct net_device * dev, struct __compat_iw_event *compat_event; struct compat_iw_point compat_wrqu; struct sk_buff *compskb; + int ptr_len; #endif /* @@ -582,6 +583,9 @@ void wireless_send_event(struct net_device * dev, nlmsg_end(skb, nlh); #ifdef CONFIG_COMPAT hdr_len = compat_event_type_size[descr->header_type]; + + /* ptr_len is remaining size in event header apart from LCP */ + ptr_len = hdr_len - IW_EV_COMPAT_LCP_LEN; event_len = hdr_len + extra_len; compskb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); @@ -612,16 +616,15 @@ void wireless_send_event(struct net_device * dev, if (descr->header_type == IW_HEADER_TYPE_POINT) { compat_wrqu.length = wrqu->data.length; compat_wrqu.flags = wrqu->data.flags; - memcpy(&compat_event->pointer, - ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, - hdr_len - IW_EV_COMPAT_LCP_LEN); + memcpy(compat_event->ptr_bytes, + ((char *)&compat_wrqu) + IW_EV_COMPAT_POINT_OFF, + ptr_len); if (extra_len) - memcpy(((char *) compat_event) + hdr_len, - extra, extra_len); + memcpy(&compat_event->ptr_bytes[ptr_len], + extra, extra_len); } else { /* extra_len must be zero, so no if (extra) needed */ - memcpy(&compat_event->pointer, wrqu, - hdr_len - IW_EV_COMPAT_LCP_LEN); + memcpy(compat_event->ptr_bytes, wrqu, ptr_len); } nlmsg_end(compskb, nlh); |