Re: WARNING: kmalloc bug in bpf_uprobe_multi_link_attach

Masami Hiramatsu
2023-12-11T11:22:35Z

On Mon, 11 Dec 2023 16:10:32 +0800
xingwei lee <xrivendell7@gmail.com> wrote:

> Hello I found a bug in net/bpf in the lastest upstream linux and lastest
> net tree.
> WARNING: kmalloc bug in bpf_uprobe_multi_link_attach

Hmm, uprobe_multi is recently introduced and it seems a normal
uprobes unlike kprobe_multi (which uses fprobe instead of kprobe).

The warning warns that the required size is bigger than INT_MAX. Maybe
too many links or uprobes were going to be allocated?

Thanks,

>
> kernel: net 28a7cb045ab700de5554193a1642917602787784
> Kernel config:
> https://github.com/google/syzkaller/commits/fc59b78e3174009510ed15f20665e7ab2435ebee
>
> in the lastestcrash like:
>
> [ 68.363836][ T8223] ------------[ cut here ]------------
> [ 68.364967][ T8223] WARNING: CPU: 2 PID: 8223 at mm/util.c:632
> kvmalloc_node+0x18a/0x1a0
> [ 68.366527][ T8223] Modules linked in:
> [ 68.367882][ T8223] CPU: 2 PID: 8223 Comm: 36d Not tainted
> 6.7.0-rc4-00146-g28a7cb045ab7 #2
> [ 68.369260][ T8223] Hardware name: QEMU Standard PC (i440FX + PIIX,
> 1996), BIOS 1.16.2-1.fc38 04/014
> [ 68.370811][ T8223] RIP: 0010:kvmalloc_node+0x18a/0x1a0
> [ 68.371689][ T8223] Code: dc 1c 00 eb aa e8 86 33 c6 ff 41 81 e4 00 20
> 00 00 31 ff 44 89 e6 e8 e5 20
> [ 68.375001][ T8223] RSP: 0018:ffffc9001088fb68 EFLAGS: 00010293
> [ 68.375989][ T8223] RAX: 0000000000000000 RBX: 00000037ffffcec8 RCX:
> ffffffff81c1a32b
> [ 68.377154][ T8223] RDX: ffff88802cc00040 RSI: ffffffff81c1a339 RDI:
> 0000000000000005
> [ 68.377950][ T8223] RBP: 0000000000000400 R08: 0000000000000005 R09:
> 0000000000000000
> [ 68.378744][ T8223] R10: 0000000000000000 R11: 0000000000000000 R12:
> 0000000000000000
> [ 68.379523][ T8223] R13: 00000000ffffffff R14: ffff888017eb4a28 R15:
> 0000000000000000
> [ 68.380307][ T8223] FS: 0000000000827380(0000)
> GS:ffff8880b9900000(0000) knlGS:0000000000000000
> [ 68.381185][ T8223] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 68.381843][ T8223] CR2: 0000000020000140 CR3: 00000000204d2000 CR4:
> 0000000000750ef0
> [ 68.382624][ T8223] PKRU: 55555554
> [ 68.382978][ T8223] Call Trace:
> [ 68.383312][ T8223] <TASK>
> [ 68.383608][ T8223] ? show_regs+0x8f/0xa0
> [ 68.384052][ T8223] ? __warn+0xe6/0x390
> [ 68.384470][ T8223] ? kvmalloc_node+0x18a/0x1a0
> [ 68.385111][ T8223] ? report_bug+0x3b9/0x580
> [ 68.385585][ T8223] ? handle_bug+0x67/0x90
> [ 68.386032][ T8223] ? exc_invalid_op+0x17/0x40
> [ 68.386503][ T8223] ? asm_exc_invalid_op+0x1a/0x20
> [ 68.387065][ T8223] ? kvmalloc_node+0x17b/0x1a0
> [ 68.387551][ T8223] ? kvmalloc_node+0x189/0x1a0
> [ 68.388051][ T8223] ? kvmalloc_node+0x18a/0x1a0
> [ 68.388537][ T8223] ? kvmalloc_node+0x189/0x1a0
> [ 68.389038][ T8223] bpf_uprobe_multi_link_attach+0x436/0xfb0
> [ 68.389633][ T8223] ? __might_fault+0x13f/0x1a0
> [ 68.390129][ T8223] ? bpf_kprobe_multi_link_attach+0x10/0x10
> [ 68.390731][ T8223] ? __fget_light+0x1fc/0x260
> [ 68.391206][ T8223] ? __sanitizer_cov_trace_switch+0x54/0x90
> [ 68.391812][ T8223] __sys_bpf+0x3ea0/0x4840
> [ 68.392267][ T8223] ? slab_free_freelist_hook+0x114/0x1e0
> [ 68.393032][ T8223] ? bpf_perf_link_attach+0x540/0x540
> [ 68.393580][ T8223] ? putname+0x12e/0x170
> [ 68.394015][ T8223] ? kmem_cache_free+0xf8/0x350
> [ 68.394509][ T8223] ? putname+0x12e/0x170
> [ 68.394948][ T8223] ? do_sys_openat2+0xb1/0x1e0
> [ 68.395442][ T8223] ? __x64_sys_creat+0xcd/0x120
> [ 68.395945][ T8223] __x64_sys_bpf+0x78/0xc0
> [ 68.396393][ T8223] ? syscall_enter_from_user_mode+0x7f/0x120
> [ 68.397040][ T8223] do_syscall_64+0x41/0x110
> [ 68.397502][ T8223] entry_SYSCALL_64_after_hwframe+0x63/0x6b
> [ 68.398098][ T8223] RIP: 0033:0x410ead
> [ 68.398498][ T8223] Code: b3 66 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f
> 1e fa 48 89 f8 48 89 f7 48 88
> [ 68.400432][ T8223] RSP: 002b:00007ffdbabd7098 EFLAGS: 00000246
> ORIG_RAX: 0000000000000141
> [ 68.401271][ T8223] RAX: ffffffffffffffda RBX: 00007ffdbabd7298 RCX:
> 0000000000410ead
> [ 68.402063][ T8223] RDX: 0000000000000040 RSI: 0000000020000340 RDI:
> 000000000000001c
> [ 68.402864][ T8223] RBP: 00007ffdbabd70b0 R08: 0000000000000000 R09:
> 0000000000000000
> [ 68.403649][ T8223] R10: 0000000000000000 R11: 0000000000000246 R12:
> 000000000049be68
> [ 68.404786][ T8223] R13: 0000000000000001 R14: 0000000000000001 R15:
> 0000000000000001
> [ 68.405574][ T8223] </TASK>
> [ 68.405890][ T8223] Kernel panic - not syncing: kernel: panic_on_warn
> set ...
> [ 68.406611][ T8223] CPU: 2 PID: 8223 Comm: 36d Not tainted
> 6.7.0-rc4-00146-g28a7cb045ab7 #2
> [ 68.407453][ T8223] Hardware name: QEMU Standard PC (i440FX + PIIX,
> 1996), BIOS 1.16.2-1.fc38 04/014
> [ 68.408386][ T8223] Call Trace:
> [ 68.408723][ T8223] <TASK>
> [ 68.409023][ T8223] dump_stack_lvl+0xd3/0x1b0
> [ 68.409484][ T8223] panic+0x6dc/0x790
> [ 68.409884][ T8223] ? panic_smp_self_stop+0xa0/0xa0
> [ 68.410408][ T8223] ? show_trace_log_lvl+0x363/0x4f0
> [ 68.410947][ T8223] ? check_panic_on_warn+0x1f/0xb0
> [ 68.411458][ T8223] ? kvmalloc_node+0x18a/0x1a0
> [ 68.411955][ T8223] check_panic_on_warn+0xab/0xb0
> [ 68.412453][ T8223] __warn+0xf2/0x390
> [ 68.412855][ T8223] ? kvmalloc_node+0x18a/0x1a0
> [ 68.413334][ T8223] report_bug+0x3b9/0x580
> [ 68.413778][ T8223] handle_bug+0x67/0x90
> [ 68.414195][ T8223] exc_invalid_op+0x17/0x40
> [ 68.414651][ T8223] asm_exc_invalid_op+0x1a/0x20
> [ 68.415150][ T8223] RIP: 0010:kvmalloc_node+0x18a/0x1a0
> [ 68.415693][ T8223] Code: dc 1c 00 eb aa e8 86 33 c6 ff 41 81 e4 00 20
> 00 00 31 ff 44 89 e6 e8 e5 20
> [ 68.417651][ T8223] RSP: 0018:ffffc9001088fb68 EFLAGS: 00010293
> [ 68.418279][ T8223] RAX: 0000000000000000 RBX: 00000037ffffcec8 RCX:
> ffffffff81c1a32b
> [ 68.419090][ T8223] RDX: ffff88802cc00040 RSI: ffffffff81c1a339 RDI:
> 0000000000000005
> [ 68.419884][ T8223] RBP: 0000000000000400 R08: 0000000000000005 R09:
> 0000000000000000
> [ 68.420678][ T8223] R10: 0000000000000000 R11: 0000000000000000 R12:
> 0000000000000000
> [ 68.421474][ T8223] R13: 00000000ffffffff R14: ffff888017eb4a28 R15:
> 0000000000000000
> [ 68.422287][ T8223] ? kvmalloc_node+0x17b/0x1a0
> [ 68.422780][ T8223] ? kvmalloc_node+0x189/0x1a0
> [ 68.423270][ T8223] ? kvmalloc_node+0x189/0x1a0
> [ 68.423769][ T8223] bpf_uprobe_multi_link_attach+0x436/0xfb0
> [ 68.424372][ T8223] ? __might_fault+0x13f/0x1a0
> [ 68.424860][ T8223] ? bpf_kprobe_multi_link_attach+0x10/0x10
> [ 68.425462][ T8223] ? __fget_light+0x1fc/0x260
> [ 68.425951][ T8223] ? __sanitizer_cov_trace_switch+0x54/0x90
> [ 68.426545][ T8223] __sys_bpf+0x3ea0/0x4840
> [ 68.427005][ T8223] ? slab_free_freelist_hook+0x114/0x1e0
> [ 68.427583][ T8223] ? bpf_perf_link_attach+0x540/0x540
> [ 68.428133][ T8223] ? putname+0x12e/0x170
> [ 68.428564][ T8223] ? kmem_cache_free+0xf8/0x350
> [ 68.429079][ T8223] ? putname+0x12e/0x170
> [ 68.429519][ T8223] ? do_sys_openat2+0xb1/0x1e0
> [ 68.430029][ T8223] ? __x64_sys_creat+0xcd/0x120
> [ 68.430536][ T8223] __x64_sys_bpf+0x78/0xc0
> [ 68.431000][ T8223] ? syscall_enter_from_user_mode+0x7f/0x120
> [ 68.431623][ T8223] do_syscall_64+0x41/0x110
> [ 68.432099][ T8223] entry_SYSCALL_64_after_hwframe+0x63/0x6b
> [ 68.432708][ T8223] RIP: 0033:0x410ead
> [ 68.433117][ T8223] Code: b3 66 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f
> 1e fa 48 89 f8 48 89 f7 48 88
> [ 68.435240][ T8223] RSP: 002b:00007ffdbabd7098 EFLAGS: 00000246
> ORIG_RAX: 0000000000000141
> [ 68.436087][ T8223] RAX: ffffffffffffffda RBX: 00007ffdbabd7298 RCX:
> 0000000000410ead
> [ 68.436898][ T8223] RDX: 0000000000000040 RSI: 0000000020000340 RDI:
> 000000000000001c
> [ 68.437697][ T8223] RBP: 00007ffdbabd70b0 R08: 0000000000000000 R09:
> 0000000000000000
> [ 68.438499][ T8223] R10: 0000000000000000 R11: 0000000000000246 R12:
> 000000000049be68
> [ 68.439305][ T8223] R13: 0000000000000001 R14: 0000000000000001 R15:
> 0000000000000001
> [ 68.440115][ T8223] </TASK>
> [ 68.440773][ T8223] Kernel Offset: disabled
> [ 68.441251][ T8223] Rebooting in 86400 seconds..
>
> =* repro.c =*
> // autogenerated by syzkaller (https://github.com/google/syzkaller)
>
> #define _GNU_SOURCE
>
> #include <endian.h>
> #include <stdint.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/syscall.h>
> #include <sys/types.h>
> #include <unistd.h>
>
> #ifndef __NR_bpf
> #define __NR_bpf 321
> #endif
>
> #define BITMASK(bf_off, bf_len) (((1ull << (bf_len)) - 1) << (bf_off))
> #define STORE_BY_BITMASK(type, htobe, addr, val, bf_off, bf_len) \
> *(type*)(addr) = \
> htobe((htobe(*(type*)(addr)) & ~BITMASK((bf_off), (bf_len))) | \
> (((type)(val) << (bf_off)) & BITMASK((bf_off), (bf_len))))
>
> uint64_t r[1] = {0xffffffffffffffff};
>
> int main(void) {
> syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
> /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
> syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul,
> /*prot=*/7ul,
> /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
> syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
> /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
> intptr_t res = 0;
> *(uint32_t*)0x20000140 = 2;
> *(uint32_t*)0x20000144 = 3;
> *(uint64_t*)0x20000148 = 0x20000200;
> *(uint8_t*)0x20000200 = 0x18;
> STORE_BY_BITMASK(uint8_t, , 0x20000201, 0, 0, 4);
> STORE_BY_BITMASK(uint8_t, , 0x20000201, 0, 4, 4);
> *(uint16_t*)0x20000202 = 0;
> *(uint32_t*)0x20000204 = 0;
> *(uint8_t*)0x20000208 = 0;
> *(uint8_t*)0x20000209 = 0;
> *(uint16_t*)0x2000020a = 0;
> *(uint32_t*)0x2000020c = 0;
> *(uint8_t*)0x20000210 = 0x95;
> *(uint8_t*)0x20000211 = 0;
> *(uint16_t*)0x20000212 = 0;
> *(uint32_t*)0x20000214 = 0;
> *(uint64_t*)0x20000150 = 0x20000240;
> memcpy((void*)0x20000240, "GPL\000", 4);
> *(uint32_t*)0x20000158 = 0;
> *(uint32_t*)0x2000015c = 0;
> *(uint64_t*)0x20000160 = 0;
> *(uint32_t*)0x20000168 = 0;
> *(uint32_t*)0x2000016c = 0;
> memset((void*)0x20000170, 0, 16);
> *(uint32_t*)0x20000180 = 0;
> *(uint32_t*)0x20000184 = 0x30;
> *(uint32_t*)0x20000188 = 0;
> *(uint32_t*)0x2000018c = 0;
> *(uint64_t*)0x20000190 = 0;
> *(uint32_t*)0x20000198 = 0;
> *(uint32_t*)0x2000019c = 0;
> *(uint64_t*)0x200001a0 = 0;
> *(uint32_t*)0x200001a8 = 0;
> *(uint32_t*)0x200001ac = 0;
> *(uint32_t*)0x200001b0 = 0;
> *(uint32_t*)0x200001b4 = 0;
> *(uint64_t*)0x200001b8 = 0;
> *(uint64_t*)0x200001c0 = 0;
> *(uint32_t*)0x200001c8 = 0;
> *(uint32_t*)0x200001cc = 0;
> res = syscall(__NR_bpf, /*cmd=*/5ul, /*arg=*/0x20000140ul,
> /*size=*/0x90ul);
> if (res != -1) r[0] = res;
> memcpy((void*)0x20000000, "./file0\000", 8);
> syscall(__NR_creat, /*file=*/0x20000000ul, /*mode=*/0ul);
> *(uint32_t*)0x20000340 = r[0];
> *(uint32_t*)0x20000344 = 0;
> *(uint32_t*)0x20000348 = 0x30;
> *(uint32_t*)0x2000034c = 0;
> *(uint64_t*)0x20000350 = 0x20000080;
> memcpy((void*)0x20000080, "./file0\000", 8);
> *(uint64_t*)0x20000358 = 0x200000c0;
> *(uint64_t*)0x200000c0 = 0;
> *(uint64_t*)0x20000360 = 0;
> *(uint64_t*)0x20000368 = 0;
> *(uint32_t*)0x20000370 = 0xffffff1f;
> *(uint32_t*)0x20000374 = 0;
> *(uint32_t*)0x20000378 = 0;
> syscall(__NR_bpf, /*cmd=*/0x1cul, /*arg=*/0x20000340ul, /*size=*/0x40ul);
> return 0;
> }
>
> =* repro.txt =*
> r0 = bpf$PROG_LOAD(0x5, &(0x7f0000000140)={0x2, 0x3,
> &(0x7f0000000200)=@framed, &(0x7f0000000240)='GPL\x00', 0x0, 0x0, 0x0, 0x0,
> 0x0, '\x00', 0x0, 0x30, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
> 0x0, 0x0, 0x0}, 0x90)
> creat(&(0x7f0000000000)='./file0\x00', 0x0)
> bpf$BPF_LINK_CREATE_XDP(0x1c, &(0x7f0000000340)={r0, 0x0, 0x30, 0x0,
> @val=@uprobe_multi={&(0x7f0000000080)='./file0\x00',
> &(0x7f00000000c0)=[0x0], 0x0, 0x0, 0xffffff1f}}, 0x40)
>
>
> See aslo
> https://gist.github.com/xrivendell7/15d43946c73aa13247b4b20b68798aaa

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>