| Message ID | 20220531215113.1100754-1-eric.dumazet@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | e0491b11c131b2040b552dc71f04d4a0b12b4139 |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf] bpf: arm64: clear prog->jited_len along prog->jited | expand |
On Tue, May 31, 2022 at 2:51 PM Eric Dumazet <eric.dumazet@gmail.com> wrote: > > From: Eric Dumazet <edumazet@google.com> > > syzbot reported an illegal copy_to_user() attempt > from bpf_prog_get_info_by_fd() [1] > > There was no repro yet on this bug, but I think > that commit 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns") > is exposing a prior bug in bpf arm64. > > bpf_prog_get_info_by_fd() looks at prog->jited_len > to determine if the JIT image can be copied out to user space. > > My theory is that syzbot managed to get a prog where prog->jited_len > has been set to 43, while prog->bpf_func has ben cleared. > > It is not clear why copy_to_user(uinsns, NULL, ulen) is triggering > this particular warning. > I thought find_vma_area(NULL) would not find a vm_struct. > As we do not hold vmap_area_lock spinlock, it might be possible > that the found vm_struct was garbage. > > [1] > usercopy: Kernel memory exposure attempt detected from vmalloc (offset 792633534417210172, size 43)! > kernel BUG at mm/usercopy.c:101! > Internal error: Oops - BUG: 0 [#1] PREEMPT SMP > Modules linked in: > CPU: 0 PID: 25002 Comm: syz-executor.1 Not tainted 5.18.0-syzkaller-10139-g8291eaafed36 #0 > Hardware name: linux,dummy-virt (DT) > pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : usercopy_abort+0x90/0x94 mm/usercopy.c:101 > lr : usercopy_abort+0x90/0x94 mm/usercopy.c:89 > sp : ffff80000b773a20 > x29: ffff80000b773a30 x28: faff80000b745000 x27: ffff80000b773b48 > x26: 0000000000000000 x25: 000000000000002b x24: 0000000000000000 > x23: 00000000000000e0 x22: ffff80000b75db67 x21: 0000000000000001 > x20: 000000000000002b x19: ffff80000b75db3c x18: 00000000fffffffd > x17: 2820636f6c6c616d x16: 76206d6f72662064 x15: 6574636574656420 > x14: 74706d6574746120 x13: 2129333420657a69 x12: 73202c3237313031 > x11: 3237313434333533 x10: 3336323937207465 x9 : 657275736f707865 > x8 : ffff80000a30c550 x7 : ffff80000b773830 x6 : ffff80000b773830 > x5 : 0000000000000000 x4 : ffff00007fbbaa10 x3 : 0000000000000000 > x2 : 0000000000000000 x1 : f7ff000028fc0000 x0 : 0000000000000064 > Call trace: > usercopy_abort+0x90/0x94 mm/usercopy.c:89 > check_heap_object mm/usercopy.c:186 [inline] > __check_object_size mm/usercopy.c:252 [inline] > __check_object_size+0x198/0x36c mm/usercopy.c:214 > check_object_size include/linux/thread_info.h:199 [inline] > check_copy_size include/linux/thread_info.h:235 [inline] > copy_to_user include/linux/uaccess.h:159 [inline] > bpf_prog_get_info_by_fd.isra.0+0xf14/0xfdc kernel/bpf/syscall.c:3993 > bpf_obj_get_info_by_fd+0x12c/0x510 kernel/bpf/syscall.c:4253 > __sys_bpf+0x900/0x2150 kernel/bpf/syscall.c:4956 > __do_sys_bpf kernel/bpf/syscall.c:5021 [inline] > __se_sys_bpf kernel/bpf/syscall.c:5019 [inline] > __arm64_sys_bpf+0x28/0x40 kernel/bpf/syscall.c:5019 > __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] > invoke_syscall+0x48/0x114 arch/arm64/kernel/syscall.c:52 > el0_svc_common.constprop.0+0x44/0xec arch/arm64/kernel/syscall.c:142 > do_el0_svc+0xa0/0xc0 arch/arm64/kernel/syscall.c:206 > el0_svc+0x44/0xb0 arch/arm64/kernel/entry-common.c:624 > el0t_64_sync_handler+0x1ac/0x1b0 arch/arm64/kernel/entry-common.c:642 > el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:581 > Code: aa0003e3 d00038c0 91248000 97fff65f (d4210000) > > Fixes: db496944fdaa ("bpf: arm64: add JIT support for multi-function programs") > Signed-off-by: Eric Dumazet <edumazet@google.com> > Reported-by: syzbot <syzkaller@googlegroups.com> Acked-by: Song Liu <songliubraving@fb.com> > --- > arch/arm64/net/bpf_jit_comp.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index 8ab4035dea2742b704dc7501b0b2128320899b1e..42f2e9a8616c3095609c182e6f50defdbe862b46 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -1478,6 +1478,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) > bpf_jit_binary_free(header); > prog->bpf_func = NULL; > prog->jited = 0; > + prog->jited_len = 0; > goto out_off; > } > bpf_jit_binary_lock_ro(header); > -- > 2.36.1.255.ge46751e96f-goog >
Hello: This patch was applied to bpf/bpf.git (master) by Daniel Borkmann <daniel@iogearbox.net>: On Tue, 31 May 2022 14:51:13 -0700 you wrote: > From: Eric Dumazet <edumazet@google.com> > > syzbot reported an illegal copy_to_user() attempt > from bpf_prog_get_info_by_fd() [1] > > There was no repro yet on this bug, but I think > that commit 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns") > is exposing a prior bug in bpf arm64. > > [...] Here is the summary with links: - [bpf] bpf: arm64: clear prog->jited_len along prog->jited https://git.kernel.org/bpf/bpf/c/e0491b11c131 You are awesome, thank you!
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 8ab4035dea2742b704dc7501b0b2128320899b1e..42f2e9a8616c3095609c182e6f50defdbe862b46 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1478,6 +1478,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) bpf_jit_binary_free(header); prog->bpf_func = NULL; prog->jited = 0; + prog->jited_len = 0; goto out_off; } bpf_jit_binary_lock_ro(header);