Two additional changes not present in the original patch: 1. Check optlen in the XDP_UMEM_REG case as well. It was added in commit c05cd36458147 ("xsk: add support to allow unaligned chunk placement") but seems like too big of a change for stable 2. copy_from_sockptr() in the context was replace copy_from_usr() because commit a7b75c5a8c414 ("net: pass a sockptr_t into ->setsockopt") was not present

[ Upstream commit 237f3cf13b20db183d3706d997eedc3c49eacd44 ]

From: Eric Dumazet edumazet@google.com

syzbot reported an illegal copy in xsk_setsockopt() [1]

Make sure to validate setsockopt() @optlen parameter.

[1]

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 xsk_setsockopt+0x909/0xa40 net/xdp/xsk.c:1420 Read of size 4 at addr ffff888028c6cde3 by task syz-executor.0/7549

CPU: 0 PID: 7549 Comm: syz-executor.0 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] xsk_setsockopt+0x909/0xa40 net/xdp/xsk.c:1420 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: 0033:0x7fb40587de69 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:00007fb40665a0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007fb4059abf80 RCX: 00007fb40587de69 RDX: 0000000000000005 RSI: 000000000000011b RDI: 0000000000000006 RBP: 00007fb4058ca47a R08: 0000000000000002 R09: 0000000000000000 R10: 0000000020001980 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007fb4059abf80 R15: 00007fff57ee4d08 </TASK>

Allocated by task 7549: 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 ffff888028c6cde0 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 [ffff888028c6cde0, ffff888028c6cde2)

The buggy address belongs to the physical page: page:ffffea0000a31b00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888028c6c9c0 pfn:0x28c6c anon flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000000800 ffff888014c41280 0000000000000000 dead000000000001 raw: ffff888028c6c9c0 0000000080800057 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 6648, tgid 6644 (syz-executor.0), ts 133906047828, free_ts 133859922223 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1533 prep_new_page mm/page_alloc.c:1540 [inline] get_page_from_freelist+0x33ea/0x3580 mm/page_alloc.c:3311 __alloc_pages+0x256/0x680 mm/page_alloc.c:4569 __alloc_pages_node include/linux/gfp.h:238 [inline] alloc_pages_node include/linux/gfp.h:261 [inline] alloc_slab_page+0x5f/0x160 mm/slub.c:2175 allocate_slab mm/slub.c:2338 [inline] new_slab+0x84/0x2f0 mm/slub.c:2391 ___slab_alloc+0xc73/0x1260 mm/slub.c:3525 __slab_alloc mm/slub.c:3610 [inline] __slab_alloc_node mm/slub.c:3663 [inline] slab_alloc_node mm/slub.c:3835 [inline] __do_kmalloc_node mm/slub.c:3965 [inline] __kmalloc_node+0x2db/0x4e0 mm/slub.c:3973 kmalloc_node include/linux/slab.h:648 [inline] __vmalloc_area_node mm/vmalloc.c:3197 [inline] __vmalloc_node_range+0x5f9/0x14a0 mm/vmalloc.c:3392 __vmalloc_node mm/vmalloc.c:3457 [inline] vzalloc+0x79/0x90 mm/vmalloc.c:3530 bpf_check+0x260/0x19010 kernel/bpf/verifier.c:21162 bpf_prog_load+0x1667/0x20f0 kernel/bpf/syscall.c:2895 __sys_bpf+0x4ee/0x810 kernel/bpf/syscall.c:5631 __do_sys_bpf kernel/bpf/syscall.c:5738 [inline] __se_sys_bpf kernel/bpf/syscall.c:5736 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 page last free pid 6650 tgid 6647 stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1140 [inline] free_unref_page_prepare+0x95d/0xa80 mm/page_alloc.c:2346 free_unref_page_list+0x5a3/0x850 mm/page_alloc.c:2532 release_pages+0x2117/0x2400 mm/swap.c:1042 tlb_batch_pages_flush mm/mmu_gather.c:98 [inline] tlb_flush_mmu_free mm/mmu_gather.c:293 [inline] tlb_flush_mmu+0x34d/0x4e0 mm/mmu_gather.c:300 tlb_finish_mmu+0xd4/0x200 mm/mmu_gather.c:392 exit_mmap+0x4b6/0xd40 mm/mmap.c:3300 __mmput+0x115/0x3c0 kernel/fork.c:1345 exit_mm+0x220/0x310 kernel/exit.c:569 do_exit+0x99e/0x27e0 kernel/exit.c:865 do_group_exit+0x207/0x2c0 kernel/exit.c:1027 get_signal+0x176e/0x1850 kernel/signal.c:2907 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:105 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline] syscall_exit_to_user_mode+0xc9/0x360 kernel/entry/common.c:212 do_syscall_64+0x10a/0x240 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Memory state around the buggy address: ffff888028c6cc80: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc ffff888028c6cd00: fa fc fc fc fa fc fc fc 00 fc fc fc 06 fc fc fc

ffff888028c6cd80: fa fc fc fc fa fc fc fc fa fc fc fc 02 fc fc fc

^ ffff888028c6ce00: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc ffff888028c6ce80: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc

Fixes: 423f38329d26 ("xsk: add umem fill queue support and mmap") Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Cc: "Björn Töpel" bjorn@kernel.org Cc: Magnus Karlsson magnus.karlsson@intel.com Cc: Maciej Fijalkowski maciej.fijalkowski@intel.com Cc: Jonathan Lemon jonathan.lemon@gmail.com Acked-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/r/20240404202738.3634547-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Shung-Hsi Yu shung-hsi.yu@suse.com --- net/xdp/xsk.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 6bb0649c028c..d5a9c43930de 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -515,6 +515,8 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname, struct xdp_umem_reg mr; struct xdp_umem *umem;

+ if (optlen < sizeof(mr)) + return -EINVAL; if (copy_from_user(&mr, optval, sizeof(mr))) return -EFAULT;

@@ -542,6 +544,8 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname, struct xsk_queue **q; int entries;

+ if (optlen < sizeof(entries)) + return -EINVAL; if (copy_from_user(&entries, optval, sizeof(entries))) return -EFAULT;