CVE-2024-35896

In the Linux kernel, the following vulnerability has been resolved:

netfilter: validate user input for expected length

I got multiple syzbot reports showing old bugs exposed

by BPF after commit 20f2505fb436 ("bpf: Try to avoid kzalloc

in cgroup/{s,g}etsockopt")

setsockopt() @optlen argument should be taken into account

before copying data.

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 do_replace net/ipv4/netfilter/ip_tables.c:1111 [inline]

BUG: KASAN: slab-out-of-bounds in do_ipt_set_ctl+0x902/0x3dd0 net/ipv4/netfilter/ip_tables.c:1627

Read of size 96 at addr ffff88802cd73da0 by task syz-executor.4/7238

CPU: 1 PID: 7238 Comm: syz-executor.4 Not tainted 6.9.0-rc2-next-20240403-syzkaller #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

kasan_check_range+0x282/0x290 mm/kasan/generic.c:189

__asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105

copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]

copy_from_sockptr include/linux/sockptr.h:55 [inline]

do_replace net/ipv4/netfilter/ip_tables.c:1111 [inline]

do_ipt_set_ctl+0x902/0x3dd0 net/ipv4/netfilter/ip_tables.c:1627

nf_setsockopt+0x295/0x2c0 net/netfilter/nf_sockopt.c:101

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+0x72/0x7a

RIP: 0033:0x7fd22067dde9

Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007fd21f9ff0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036

RAX: ffffffffffffffda RBX: 00007fd2207abf80 RCX: 00007fd22067dde9

RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000003

RBP: 00007fd2206ca47a R08: 0000000000000001 R09: 0000000000000000

R10: 0000000020000880 R11: 0000000000000246 R12: 0000000000000000

R13: 000000000000000b R14: 00007fd2207abf80 R15: 00007ffd2d0170d8

</TASK>

Allocated by task 7238:

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:4069 [inline]

__kmalloc_noprof+0x200/0x410 mm/slub.c:4082

kmalloc_noprof include/linux/slab.h:664 [inline]

__cgroup_bpf_run_filter_setsockopt+0xd47/0x1050 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+0x72/0x7a

The buggy address belongs to the object at ffff88802cd73da0

which belongs to the cache kmalloc-8 of size 8

The buggy address is located 0 bytes inside of

allocated 1-byte region [ffff88802cd73da0, ffff88802cd73da1)

The buggy address belongs to the physical page:

page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802cd73020 pfn:0x2cd73

flags: 0xfff80000000000(node=0|zone=1|lastcpupid=0xfff)

page_type: 0xffffefff(slab)

raw: 00fff80000000000 ffff888015041280 dead000000000100 dead000000000122

raw: ffff88802cd73020 000000008080007f 00000001ffffefff 00

---truncated---