* [PATCH bpf] bpf: arm64: clear prog->jited_len along prog->jited
@ 2022-05-31 21:51 Eric Dumazet
2022-05-31 22:17 ` Song Liu
2022-05-31 22:30 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Eric Dumazet @ 2022-05-31 21:51 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Zi Shen Lim
Cc: David S . Miller, netdev, Eric Dumazet, Eric Dumazet, bpf, syzbot
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>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf] bpf: arm64: clear prog->jited_len along prog->jited
2022-05-31 21:51 [PATCH bpf] bpf: arm64: clear prog->jited_len along prog->jited Eric Dumazet
@ 2022-05-31 22:17 ` Song Liu
2022-05-31 22:30 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Song Liu @ 2022-05-31 22:17 UTC (permalink / raw)
To: Eric Dumazet
Cc: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Zi Shen Lim, David S . Miller, netdev, Eric Dumazet, bpf, syzbot
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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf] bpf: arm64: clear prog->jited_len along prog->jited
2022-05-31 21:51 [PATCH bpf] bpf: arm64: clear prog->jited_len along prog->jited Eric Dumazet
2022-05-31 22:17 ` Song Liu
@ 2022-05-31 22:30 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-05-31 22:30 UTC (permalink / raw)
To: Eric Dumazet
Cc: ast, daniel, andrii, zlim.lnx, davem, netdev, edumazet, bpf, syzkaller
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!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-05-31 21:51 [PATCH bpf] bpf: arm64: clear prog->jited_len along prog->jited Eric Dumazet
2022-05-31 22:17 ` Song Liu
2022-05-31 22:30 ` patchwork-bot+netdevbpf
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