[syzbot] [bluetooth?] KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 707081b61156 Merge branch 'for-next/core', remote-tracking..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=14a081d3180000
kernel config: https://syzkaller.appspot.com/x/.config?x=caeac3f3565b057a
dashboard link: https://syzkaller.appspot.com/bug?extid=8a1d152fba6b41f760ae
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16a2a955180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15c6098d180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6cad68bf7532/disk-707081b6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1a27e5400778/vmlinux-707081b6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/67dfc53755d0/Image-707081b6.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8a1d15...@syzkaller.appspotmail.com

==================================================================
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 l2cap_sock_setsockopt+0x2070/0x2934 net/bluetooth/l2cap_sock.c:962
Read of size 4 at addr ffff0000cbfa73c3 by task syz-executor258/6168

CPU: 1 PID: 6168 Comm: syz-executor258 Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:291
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:298
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x178/0x518 mm/kasan/report.c:488
kasan_report+0xd8/0x138 mm/kasan/report.c:601
__asan_report_load_n_noabort+0x1c/0x28 mm/kasan/report_generic.c:391
copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
copy_from_sockptr include/linux/sockptr.h:55 [inline]
l2cap_sock_setsockopt+0x2070/0x2934 net/bluetooth/l2cap_sock.c:962
do_sock_setsockopt+0x2a0/0x4e0 net/socket.c:2311
__sys_setsockopt+0x128/0x1a8 net/socket.c:2334
__do_sys_setsockopt net/socket.c:2343 [inline]
__se_sys_setsockopt net/socket.c:2340 [inline]
__arm64_sys_setsockopt+0xb8/0xd4 net/socket.c:2340
__invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

Allocated by task 6168:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x40/0x78 mm/kasan/common.c:68
kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:575
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slub.c:3981 [inline]
__kmalloc+0x2bc/0x5d4 mm/slub.c:3994
kmalloc include/linux/slab.h:594 [inline]
__cgroup_bpf_run_filter_setsockopt+0xa94/0xd1c kernel/bpf/cgroup.c:1872
do_sock_setsockopt+0x498/0x4e0 net/socket.c:2293
__sys_setsockopt+0x128/0x1a8 net/socket.c:2334
__do_sys_setsockopt net/socket.c:2343 [inline]
__se_sys_setsockopt net/socket.c:2340 [inline]
__arm64_sys_setsockopt+0xb8/0xd4 net/socket.c:2340
__invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

The buggy address belongs to the object at ffff0000cbfa73c0
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 [ffff0000cbfa73c0, ffff0000cbfa73c2)

The buggy address belongs to the physical page:
page:00000000512b024c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10bfa7
anon flags: 0x5ffc00000000800(slab|node=0|zone=2|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 05ffc00000000800 ffff0000c0001280 0000000000000000 dead000000000001
raw: 0000000000000000 0000000080800080 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff0000cbfa7280: 05 fc fc fc 00 fc fc fc 00 fc fc fc 00 fc fc fc
ffff0000cbfa7300: 05 fc fc fc 05 fc fc fc 05 fc fc fc fa fc fc fc
>ffff0000cbfa7380: fa fc fc fc 00 fc fc fc 02 fc fc fc 05 fc fc fc
^
ffff0000cbfa7400: 00 fc fc fc 00 fc fc fc 00 fc fc fc 05 fc fc fc
ffff0000cbfa7480: 05 fc fc fc 05 fc fc fc 05 fc fc fc fa fc fc fc
==================================================================


---
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[Edward Adam Davis]

please test oob in rfcomm_sock_setsockopt

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fe46a7dd189e

diff --git a/net/socket.c b/net/socket.c
index e5f3af49a8b6..d5b2ab6c859c 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 < 4)
+ return -EINVAL;
+
sock = sockfd_lookup_light(fd, &err, &fput_needed);
if (!sock)
return err;

[Hillf Danton]

On Thu, 04 Apr 2024 23:55:25 -0700

> syzbot found the following issue on:
>
> HEAD commit: 707081b61156 Merge branch 'for-next/core', remote-tracking..
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15c6098d180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fe46a7dd189e

--- x/net/bluetooth/l2cap_sock.c
+++ y/net/bluetooth/l2cap_sock.c
@@ -960,7 +960,7 @@ static int l2cap_sock_setsockopt(struct
break;
}

- if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
+ if (optlen < sizeof(u32) || copy_from_sockptr(&opt, optval, sizeof(u32))) {
err = -EFAULT;
break;
}
--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+8a1d15...@syzkaller.appspotmail.com

Tested on:

commit: fe46a7dd Merge tag 'sound-6.9-rc1' of git://git.kernel..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=11b55605180000
kernel config: https://syzkaller.appspot.com/x/.config?x=66b62423625ca66a

dashboard link: https://syzkaller.appspot.com/bug?extid=8a1d152fba6b41f760ae
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

patch: https://syzkaller.appspot.com/x/patch.diff?x=14c06aa9180000

Note: testing is done by a robot and is best-effort only.

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+8a1d15...@syzkaller.appspotmail.com

Tested on:

commit: fe46a7dd Merge tag 'sound-6.9-rc1' of git://git.kernel..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=136840bd180000

kernel config: https://syzkaller.appspot.com/x/.config?x=66b62423625ca66a
dashboard link: https://syzkaller.appspot.com/bug?extid=8a1d152fba6b41f760ae
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

patch: https://syzkaller.appspot.com/x/patch.diff?x=13d15f19180000