Hi, On 12/11/2023 4:12 PM, xingwei lee wrote: > Sorry for containing HTML part, repeat the mail > 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 > > kernel: net 28a7cb045ab700de5554193a1642917602787784 > Kernel config: https://github.com/google/syzkaller/commits/fc59b78e3174009510ed15f20665e7ab2435ebee > > in the lastest net tree, the crash 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 It seems a big attr->link_create.uprobe_multi.cnt is passed to bpf_uprobe_multi_link_attach(). Could you please try the first patch in the following patch set ? https://lore.kernel.org/bpf/20231211112843.4147157-1-houtao@xxxxxxxxxxxxxxx/T/#t > [ 68.389633][ T8223] ? __might_fault+0x13f/0x1a0 > [ 68.390129][ T8223] ? bpf_kprobe_multi_link_attach+0x10/0x10 SNIP > 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); 0x20000350 is the address of attr->link_create.uprobe_multi.path. > *(uint64_t*)0x20000358 = 0x200000c0; > *(uint64_t*)0x200000c0 = 0; > *(uint64_t*)0x20000360 = 0; > *(uint64_t*)0x20000368 = 0; > *(uint32_t*)0x20000370 = 0xffffff1f; The value of attr->link_create.uprobe_multi.cnt is 0xffffff1f, so 0xffffff1f * sizeof(bpf_uprobe) will be greater than INT_MAX, and triggers the warning in mm/util.c: /* Don't even allow crazy sizes */ if (unlikely(size > INT_MAX)) { WARN_ON_ONCE(!(flags & __GFP_NOWARN)); return NULL; } Adding __GFP_NOWARN when doing kvcalloc() can fix the warning. > *(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 > > .
