[syzbot] [arm?] [netfilter?] KASAN: slab-out-of-bounds Read in do_csum

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 908f31f2a05b 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=155e0463280000
kernel config: https://syzkaller.appspot.com/x/.config?x=c1058fe68f4b7b2c
dashboard link: https://syzkaller.appspot.com/bug?extid=4a9f9820bd8d302e22f7
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16bc548d280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=135bba3b280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/87d095820229/disk-908f31f2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a1bf67af9675/vmlinux-908f31f2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7784a88b37e8/Image-908f31f2.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4a9f98...@syzkaller.appspotmail.com

netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
==================================================================
BUG: KASAN: slab-out-of-bounds in do_csum+0x44/0x254 arch/arm64/lib/csum.c:39
Read of size 4294966928 at addr ffff0000d7ac0170 by task syz-executor412/5975

CPU: 0 PID: 5975 Comm: syz-executor412 Not tainted 6.4.0-rc4-syzkaller-g908f31f2a05b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
__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:351 [inline]
print_report+0x174/0x514 mm/kasan/report.c:462
kasan_report+0xd4/0x130 mm/kasan/report.c:572
kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:187
__kasan_check_read+0x20/0x30 mm/kasan/shadow.c:31
do_csum+0x44/0x254 arch/arm64/lib/csum.c:39
csum_partial+0x30/0x58 lib/checksum.c:128
gso_make_checksum include/linux/skbuff.h:4928 [inline]
__udp_gso_segment+0xaf4/0x1bc4 net/ipv4/udp_offload.c:332
udp6_ufo_fragment+0x540/0xca0 net/ipv6/udp_offload.c:47
ipv6_gso_segment+0x5cc/0x1760 net/ipv6/ip6_offload.c:119
skb_mac_gso_segment+0x2b4/0x5b0 net/core/gro.c:141
__skb_gso_segment+0x250/0x3d0 net/core/dev.c:3401
skb_gso_segment include/linux/netdevice.h:4859 [inline]
validate_xmit_skb+0x364/0xdbc net/core/dev.c:3659
validate_xmit_skb_list+0x94/0x130 net/core/dev.c:3709
sch_direct_xmit+0xe8/0x548 net/sched/sch_generic.c:327
__dev_xmit_skb net/core/dev.c:3805 [inline]
__dev_queue_xmit+0x147c/0x3318 net/core/dev.c:4210
dev_queue_xmit include/linux/netdevice.h:3085 [inline]
packet_xmit+0x6c/0x318 net/packet/af_packet.c:276
packet_snd net/packet/af_packet.c:3081 [inline]
packet_sendmsg+0x376c/0x4c98 net/packet/af_packet.c:3113
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg net/socket.c:747 [inline]
__sys_sendto+0x3b4/0x538 net/socket.c:2144
__do_sys_sendto net/socket.c:2156 [inline]
__se_sys_sendto net/socket.c:2152 [inline]
__arm64_sys_sendto+0xd8/0xf8 net/socket.c:2152
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:191
el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

Allocated by task 5975:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4c/0x7c mm/kasan/common.c:52
kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:510
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:196 [inline]
__do_kmalloc_node mm/slab_common.c:966 [inline]
__kmalloc_node_track_caller+0xd0/0x1c0 mm/slab_common.c:986
kmalloc_reserve+0x120/0x240 net/core/skbuff.c:585
__alloc_skb+0x1c8/0x3d8 net/core/skbuff.c:654
skb_segment+0xa80/0x32f0 net/core/skbuff.c:4516
__udp_gso_segment+0x5d0/0x1bc4 net/ipv4/udp_offload.c:290
udp6_ufo_fragment+0x540/0xca0 net/ipv6/udp_offload.c:47
ipv6_gso_segment+0x5cc/0x1760 net/ipv6/ip6_offload.c:119
skb_mac_gso_segment+0x2b4/0x5b0 net/core/gro.c:141
__skb_gso_segment+0x250/0x3d0 net/core/dev.c:3401
skb_gso_segment include/linux/netdevice.h:4859 [inline]
validate_xmit_skb+0x364/0xdbc net/core/dev.c:3659
validate_xmit_skb_list+0x94/0x130 net/core/dev.c:3709
sch_direct_xmit+0xe8/0x548 net/sched/sch_generic.c:327
__dev_xmit_skb net/core/dev.c:3805 [inline]
__dev_queue_xmit+0x147c/0x3318 net/core/dev.c:4210
dev_queue_xmit include/linux/netdevice.h:3085 [inline]
packet_xmit+0x6c/0x318 net/packet/af_packet.c:276
packet_snd net/packet/af_packet.c:3081 [inline]
packet_sendmsg+0x376c/0x4c98 net/packet/af_packet.c:3113
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg net/socket.c:747 [inline]
__sys_sendto+0x3b4/0x538 net/socket.c:2144
__do_sys_sendto net/socket.c:2156 [inline]
__se_sys_sendto net/socket.c:2152 [inline]
__arm64_sys_sendto+0xd8/0xf8 net/socket.c:2152
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:191
el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

The buggy address belongs to the object at ffff0000d7ac0000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 368 bytes inside of
allocated 8192-byte region [ffff0000d7ac0000, ffff0000d7ac2000)

The buggy address belongs to the physical page:
page:000000002bfc4c52 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x117ac0
head:000000002bfc4c52 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 05ffc00000010200 ffff0000c0002c00 fffffc00035e7e00 0000000000000002
raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff0000d7ac1f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff0000d7ac1f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000d7ac2000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff0000d7ac2080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff0000d7ac2100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
================================================================================
UBSAN: shift-out-of-bounds in arch/arm64/lib/csum.c:116:15
shift exponent 3008 is too large for 64-bit type 'u64' (aka 'unsigned long long')
CPU: 0 PID: 5975 Comm: syz-executor412 Tainted: G B 6.4.0-rc4-syzkaller-g908f31f2a05b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
dump_stack+0x1c/0x28 lib/dump_stack.c:113
ubsan_epilogue lib/ubsan.c:217 [inline]
__ubsan_handle_shift_out_of_bounds+0x2f4/0x36c lib/ubsan.c:387
do_csum+0x238/0x254 arch/arm64/lib/csum.c:116
csum_partial+0x30/0x58 lib/checksum.c:128
gso_make_checksum include/linux/skbuff.h:4928 [inline]
__udp_gso_segment+0xaf4/0x1bc4 net/ipv4/udp_offload.c:332
udp6_ufo_fragment+0x540/0xca0 net/ipv6/udp_offload.c:47
ipv6_gso_segment+0x5cc/0x1760 net/ipv6/ip6_offload.c:119
skb_mac_gso_segment+0x2b4/0x5b0 net/core/gro.c:141
__skb_gso_segment+0x250/0x3d0 net/core/dev.c:3401
skb_gso_segment include/linux/netdevice.h:4859 [inline]
validate_xmit_skb+0x364/0xdbc net/core/dev.c:3659
validate_xmit_skb_list+0x94/0x130 net/core/dev.c:3709
sch_direct_xmit+0xe8/0x548 net/sched/sch_generic.c:327
__dev_xmit_skb net/core/dev.c:3805 [inline]
__dev_queue_xmit+0x147c/0x3318 net/core/dev.c:4210
dev_queue_xmit include/linux/netdevice.h:3085 [inline]
packet_xmit+0x6c/0x318 net/packet/af_packet.c:276
packet_snd net/packet/af_packet.c:3081 [inline]
packet_sendmsg+0x376c/0x4c98 net/packet/af_packet.c:3113
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg net/socket.c:747 [inline]
__sys_sendto+0x3b4/0x538 net/socket.c:2144
__do_sys_sendto net/socket.c:2156 [inline]
__se_sys_sendto net/socket.c:2152 [inline]
__arm64_sys_sendto+0xd8/0xf8 net/socket.c:2152
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:191
el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
================================================================================
================================================================================
UBSAN: shift-out-of-bounds in arch/arm64/lib/csum.c:116:25
shift exponent 3008 is too large for 64-bit type 'u64' (aka 'unsigned long long')
CPU: 0 PID: 5975 Comm: syz-executor412 Tainted: G B 6.4.0-rc4-syzkaller-g908f31f2a05b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
dump_stack+0x1c/0x28 lib/dump_stack.c:113
ubsan_epilogue lib/ubsan.c:217 [inline]
__ubsan_handle_shift_out_of_bounds+0x2f4/0x36c lib/ubsan.c:387
do_csum+0x250/0x254 arch/arm64/lib/csum.c:116
csum_partial+0x30/0x58 lib/checksum.c:128
gso_make_checksum include/linux/skbuff.h:4928 [inline]
__udp_gso_segment+0xaf4/0x1bc4 net/ipv4/udp_offload.c:332
udp6_ufo_fragment+0x540/0xca0 net/ipv6/udp_offload.c:47
ipv6_gso_segment+0x5cc/0x1760 net/ipv6/ip6_offload.c:119
skb_mac_gso_segment+0x2b4/0x5b0 net/core/gro.c:141
__skb_gso_segment+0x250/0x3d0 net/core/dev.c:3401
skb_gso_segment include/linux/netdevice.h:4859 [inline]
validate_xmit_skb+0x364/0xdbc net/core/dev.c:3659
validate_xmit_skb_list+0x94/0x130 net/core/dev.c:3709
sch_direct_xmit+0xe8/0x548 net/sched/sch_generic.c:327
__dev_xmit_skb net/core/dev.c:3805 [inline]
__dev_queue_xmit+0x147c/0x3318 net/core/dev.c:4210
dev_queue_xmit include/linux/netdevice.h:3085 [inline]
packet_xmit+0x6c/0x318 net/packet/af_packet.c:276
packet_snd net/packet/af_packet.c:3081 [inline]
packet_sendmsg+0x376c/0x4c98 net/packet/af_packet.c:3113
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg net/socket.c:747 [inline]
__sys_sendto+0x3b4/0x538 net/socket.c:2144
__do_sys_sendto net/socket.c:2156 [inline]
__se_sys_sendto net/socket.c:2152 [inline]
__arm64_sys_sendto+0xd8/0xf8 net/socket.c:2152
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:191
el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
================================================================================
skb len=9070 headroom=178 headlen=9070 tailroom=6816
mac=(178,14) net=(192,176) trans=368
shinfo(txflags=0 nr_frags=0 gso(size=7321 type=131074 segs=0))
csum(0x0 ip_summed=0 complete_sw=0 valid=0 level=0)
hash(0x0 sw=0 l4=0) proto=0x86dd pkttype=0 iif=0
dev name=erspan0 feat=0x0000000000006869
sk family=17 type=3 proto=0
skb linear: 00000000: 0c 2c ff f5 7b 01 6d 27 63 bd 56 37 86 dd 39 8d
skb linear: 00000010: 53 75 03 e5 2b 02 59 1f 11 1e e6 16 d5 c0 18 43
skb linear: 00000020: 74 a7 ff e4 ec 55 e0 65 47 86 a7 01 00 93 5b a5
skb linear: 00000030: 14 d4 08 08 ef a0 11 10 16 01 84 2f d0 8d 49 a4
skb linear: 00000040: 7e ff 71 bc 41 31 fe 4c 1f 99 bf 00 a9 00 00 00
skb linear: 00000050: 08 d1 84 3e 77 0a fd 6e 9e f5 83 7d bd 00 00 00
skb linear: 00000060: 00 53 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000070: 00 00 00 00 00 00 11 00 00 00 05 00 00 00 01 00
skb linear: 00000080: 00 06 89 7b 42 8e 75 eb 00 00 00 00 00 00 00 00
skb linear: 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000f0: 00 00 00 00 00 00 65 72 73 70 61 6e 30 00 00 00
skb linear: 00000100: 00 00 00 00 00 00 05 00 00 00 00 00 00 00 00 00
skb linear: 00000110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
------------[ cut here ]------------
erspan0: caps=(0x0000000000006869, 0x0000000000000000)
WARNING: CPU: 0 PID: 5975 at net/core/dev.c:3230 skb_warn_bad_offload+0x160/0x194 net/core/dev.c:3228
Modules linked in:
CPU: 0 PID: 5975 Comm: syz-executor412 Tainted: G B 6.4.0-rc4-syzkaller-g908f31f2a05b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : skb_warn_bad_offload+0x160/0x194 net/core/dev.c:3228
lr : skb_warn_bad_offload+0x160/0x194 net/core/dev.c:3228
sp : ffff800096947280
x29: ffff800096947280 x28: dfff800000000000 x27: ffff0000d2086000
x26: 0000000000000020 x25: 1fffe0001ae170d8 x24: ffff80008c6f97c0
x23: dfff800000000000 x22: ffff0000d70b8658 x21: ffff0000d2086000
x20: ffff0000d2086000 x19: ffff0000d20860f0 x18: 0000000000000000
x17: 0000000000000000 x16: ffff80008a4342bc x15: 0000000000000203
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000001
x11: 0000000000000201 x10: 0000000000000000 x9 : e71a9b1dab1be800
x8 : e71a9b1dab1be800 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800096946b78 x4 : ffff80008df9ed80 x3 : ffff800080597be8
x2 : 0000000000000001 x1 : 0000000000000201 x0 : 0000000000000000
Call trace:
skb_warn_bad_offload+0x160/0x194 net/core/dev.c:3228
__skb_gso_segment+0x2f8/0x3d0 net/core/dev.c:3404
skb_gso_segment include/linux/netdevice.h:4859 [inline]
validate_xmit_skb+0x364/0xdbc net/core/dev.c:3659
validate_xmit_skb_list+0x94/0x130 net/core/dev.c:3709
sch_direct_xmit+0xe8/0x548 net/sched/sch_generic.c:327
__dev_xmit_skb net/core/dev.c:3805 [inline]
__dev_queue_xmit+0x147c/0x3318 net/core/dev.c:4210
dev_queue_xmit include/linux/netdevice.h:3085 [inline]
packet_xmit+0x6c/0x318 net/packet/af_packet.c:276
packet_snd net/packet/af_packet.c:3081 [inline]
packet_sendmsg+0x376c/0x4c98 net/packet/af_packet.c:3113
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg net/socket.c:747 [inline]
__sys_sendto+0x3b4/0x538 net/socket.c:2144
__do_sys_sendto net/socket.c:2156 [inline]
__se_sys_sendto net/socket.c:2152 [inline]
__arm64_sys_sendto+0xd8/0xf8 net/socket.c:2152
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:191
el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
irq event stamp: 128240
hardirqs last enabled at (128240): [<ffff80008a4321bc>] __exit_to_kernel_mode arch/arm64/kernel/entry-common.c:84 [inline]
hardirqs last enabled at (128240): [<ffff80008a4321bc>] exit_to_kernel_mode+0xdc/0x10c arch/arm64/kernel/entry-common.c:94
hardirqs last disabled at (128239): [<ffff80008a42fdf4>] __el1_irq arch/arm64/kernel/entry-common.c:470 [inline]
hardirqs last disabled at (128239): [<ffff80008a42fdf4>] el1_interrupt+0x24/0x68 arch/arm64/kernel/entry-common.c:488
softirqs last enabled at (128206): [<ffff80008861d870>] spin_unlock_bh include/linux/spinlock.h:395 [inline]
softirqs last enabled at (128206): [<ffff80008861d870>] release_sock+0x15c/0x1b0 net/core/sock.c:3495
softirqs last disabled at (128224): [<ffff8000886a21f0>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---


---
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#syz undup

[Will Deacon]

[+Robin as he's had fun with the checksum code in the past]

On Mon, Aug 28, 2023 at 03:04:44AM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 908f31f2a05b 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=155e0463280000
> kernel config: https://syzkaller.appspot.com/x/.config?x=c1058fe68f4b7b2c
> dashboard link: https://syzkaller.appspot.com/bug?extid=4a9f9820bd8d302e22f7
> compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
> userspace arch: arm64
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16bc548d280000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=135bba3b280000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/87d095820229/disk-908f31f2.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/a1bf67af9675/vmlinux-908f31f2.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/7784a88b37e8/Image-908f31f2.gz.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+4a9f98...@syzkaller.appspotmail.com
>
> netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
> netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in do_csum+0x44/0x254 arch/arm64/lib/csum.c:39
> Read of size 4294966928 at addr ffff0000d7ac0170 by task syz-executor412/5975

Judging by the UBSAN errors:

| shift exponent 3008 is too large for 64-bit type 'u64' (aka 'unsigned long long')

We're probably being passed a negative 'len' argument. It looks like the
generic version in lib/checksum.c rejects that early, so maybe we should
do the same in the arch code?

Will

[Robin Murphy]

Yup, that looks suspiciously "-368"-shaped...

> Judging by the UBSAN errors:
>
> | shift exponent 3008 is too large for 64-bit type 'u64' (aka 'unsigned long long')
>
> We're probably being passed a negative 'len' argument. It looks like the
> generic version in lib/checksum.c rejects that early, so maybe we should
> do the same in the arch code?

Hmm, indeed I can offer no explanation as to why I put "if (len == 0)"
there rather than "if (len <= 0)" like literally every other C
implementation* :/

Cheers,
Robin.


*apart from Loongarch who didn't exist at the time, but appear to have
dutifully copy-pasted the same bug.

[Will Deacon]

I've made that change:

https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/commit/?h=for-next/fixes&id=8bd795fedb8450ecbef18eeadbd23ed8fc7630f5

Cheers,

Will

[Robin Murphy]

If you want it,

Acked-by: Robin Murphy <robin....@arm.com>

>
> Cheers,
>
> Will