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* [PATCH -next v2] bpf: Add oversize check before call kvmalloc()
@ 2021-12-01  1:33 Bixuan Cui
  2021-12-01 11:23 ` Leon Romanovsky
  0 siblings, 1 reply; 2+ messages in thread
From: Bixuan Cui @ 2021-12-01  1:33 UTC (permalink / raw)
  To: linux-kernel, bpf, netdev, andrii.nakryiko
  Cc: cuibixuan, ast, daniel, andrii, kafai, songliubraving, yhs,
	john.fastabend, kpsingh

Commit 7661809d493b ("mm: don't allow oversized kvmalloc() calls") add
the oversize check. When the allocation is larger than what kvmalloc()
supports, the following warning triggered:

WARNING: CPU: 1 PID: 372 at mm/util.c:597 kvmalloc_node+0x111/0x120
mm/util.c:597
Modules linked in:
CPU: 1 PID: 372 Comm: syz-executor.4 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:kvmalloc_node+0x111/0x120 mm/util.c:597
Code: 01 00 00 00 4c 89 e7 e8 7d f7 0c 00 49 89 c5 e9 69 ff ff ff e8 60
20 d1 ff 41 89 ed 41 81 cd 00 20 01 00 eb 95 e8 4f 20 d1 ff <0f> 0b e9
4c ff ff ff 0f 1f 84 00 00 00 00 00 55 48 89 fd 53 e8 36
RSP: 0018:ffffc90002bf7c98 EFLAGS: 00010216
RAX: 00000000000000ec RBX: 1ffff9200057ef9f RCX: ffffc9000ac63000
RDX: 0000000000040000 RSI: ffffffff81a6a621 RDI: 0000000000000003
RBP: 0000000000102cc0 R08: 000000007fffffff R09: 00000000ffffffff
R10: ffffffff81a6a5de R11: 0000000000000000 R12: 00000000ffff9aaa
R13: 0000000000000000 R14: 00000000ffffffff R15: 0000000000000000
FS:  00007f05f2573700(0000) GS:ffff8880b9d00000(0000)
knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f424000 CR3: 0000000027d2c000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kvmalloc include/linux/slab.h:741 [inline]
 map_lookup_elem kernel/bpf/syscall.c:1090 [inline]
 __sys_bpf+0x3a5b/0x5f00 kernel/bpf/syscall.c:4603
 __do_sys_bpf kernel/bpf/syscall.c:4722 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4720 [inline]
 __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4720
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The type of 'value_size' is u32, its value may exceed INT_MAX.

Reported-by: syzbot+cecf5b7071a0dfb76530@syzkaller.appspotmail.com
Signed-off-by: Bixuan Cui <cuibixuan@linux.alibaba.com>
---
Changes in v2:
* Change the err from -EINVAL to -E2BIG;
* Change "goto err_put" to "goto free_key";

 kernel/bpf/syscall.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 1033ee8..30aabdd 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1094,6 +1094,10 @@ static int map_lookup_elem(union bpf_attr *attr)
 	}
 
 	value_size = bpf_map_value_size(map);
+	if (value_size > INT_MAX) {
+		err = -E2BIG;
+		goto free_key;
+	}
 
 	err = -ENOMEM;
 	value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH -next v2] bpf: Add oversize check before call kvmalloc()
  2021-12-01  1:33 [PATCH -next v2] bpf: Add oversize check before call kvmalloc() Bixuan Cui
@ 2021-12-01 11:23 ` Leon Romanovsky
  0 siblings, 0 replies; 2+ messages in thread
From: Leon Romanovsky @ 2021-12-01 11:23 UTC (permalink / raw)
  To: Bixuan Cui
  Cc: linux-kernel, bpf, netdev, andrii.nakryiko, ast, daniel, andrii,
	kafai, songliubraving, yhs, john.fastabend, kpsingh

On Wed, Dec 01, 2021 at 09:33:22AM +0800, Bixuan Cui wrote:
> Commit 7661809d493b ("mm: don't allow oversized kvmalloc() calls") add
> the oversize check. When the allocation is larger than what kvmalloc()
> supports, the following warning triggered:
> 
> WARNING: CPU: 1 PID: 372 at mm/util.c:597 kvmalloc_node+0x111/0x120
> mm/util.c:597
> Modules linked in:
> CPU: 1 PID: 372 Comm: syz-executor.4 Not tainted 5.15.0-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:kvmalloc_node+0x111/0x120 mm/util.c:597
> Code: 01 00 00 00 4c 89 e7 e8 7d f7 0c 00 49 89 c5 e9 69 ff ff ff e8 60
> 20 d1 ff 41 89 ed 41 81 cd 00 20 01 00 eb 95 e8 4f 20 d1 ff <0f> 0b e9
> 4c ff ff ff 0f 1f 84 00 00 00 00 00 55 48 89 fd 53 e8 36
> RSP: 0018:ffffc90002bf7c98 EFLAGS: 00010216
> RAX: 00000000000000ec RBX: 1ffff9200057ef9f RCX: ffffc9000ac63000
> RDX: 0000000000040000 RSI: ffffffff81a6a621 RDI: 0000000000000003
> RBP: 0000000000102cc0 R08: 000000007fffffff R09: 00000000ffffffff
> R10: ffffffff81a6a5de R11: 0000000000000000 R12: 00000000ffff9aaa
> R13: 0000000000000000 R14: 00000000ffffffff R15: 0000000000000000
> FS:  00007f05f2573700(0000) GS:ffff8880b9d00000(0000)
> knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b2f424000 CR3: 0000000027d2c000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  kvmalloc include/linux/slab.h:741 [inline]
>  map_lookup_elem kernel/bpf/syscall.c:1090 [inline]
>  __sys_bpf+0x3a5b/0x5f00 kernel/bpf/syscall.c:4603
>  __do_sys_bpf kernel/bpf/syscall.c:4722 [inline]
>  __se_sys_bpf kernel/bpf/syscall.c:4720 [inline]
>  __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4720
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> The type of 'value_size' is u32, its value may exceed INT_MAX.
> 
> Reported-by: syzbot+cecf5b7071a0dfb76530@syzkaller.appspotmail.com
> Signed-off-by: Bixuan Cui <cuibixuan@linux.alibaba.com>
> ---
> Changes in v2:
> * Change the err from -EINVAL to -E2BIG;
> * Change "goto err_put" to "goto free_key";

Please fix kvmalloc instead.
https://lore.kernel.org/all/YadOjJXMTjP85MQx@unreal

diff --git a/mm/util.c b/mm/util.c
index 741ba32a43ac..3749f4a16ab9 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -594,7 +594,7 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
                return ret;

        /* Don't even allow crazy sizes */
-       if (WARN_ON_ONCE(size > INT_MAX))
+       if (size > INT_MAX)
                return NULL;

        return __vmalloc_node(size, 1, flags, node,


> 
>  kernel/bpf/syscall.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 1033ee8..30aabdd 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -1094,6 +1094,10 @@ static int map_lookup_elem(union bpf_attr *attr)
>  	}
>  
>  	value_size = bpf_map_value_size(map);
> +	if (value_size > INT_MAX) {
> +		err = -E2BIG;
> +		goto free_key;
> +	}
>  
>  	err = -ENOMEM;
>  	value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
> -- 
> 1.8.3.1
> 

^ permalink raw reply related	[flat|nested] 2+ messages in thread

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2021-12-01  1:33 [PATCH -next v2] bpf: Add oversize check before call kvmalloc() Bixuan Cui
2021-12-01 11:23 ` Leon Romanovsky

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