Commit 7661809d493b ("mm: don't allow oversized kvmalloc() calls") add the
oversize check. When the allocation is larger than what kmalloc() supports,
the following warning triggered:
WARNING: CPU: 0 PID: 8408 at mm/util.c:597 kvmalloc_node+0x108/0x110 mm/util.c:597
Modules linked in:
CPU: 0 PID: 8408 Comm: syz-executor221 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:kvmalloc_node+0x108/0x110 mm/util.c:597
Call Trace:
kvmalloc include/linux/mm.h:806 [inline]
kvmalloc_array include/linux/mm.h:824 [inline]
kvcalloc include/linux/mm.h:829 [inline]
check_btf_line kernel/bpf/verifier.c:9925 [inline]
check_btf_info kernel/bpf/verifier.c:10049 [inline]
bpf_check+0xd634/0x150d0 kernel/bpf/verifier.c:13759
bpf_prog_load kernel/bpf/syscall.c:2301 [inline]
__sys_bpf+0x11181/0x126e0 kernel/bpf/syscall.c:4587
__do_sys_bpf kernel/bpf/syscall.c:4691 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4689 [inline]
__x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4689
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Reported-by: [email protected]
Signed-off-by: Bixuan Cui <[email protected]>
---
kernel/bpf/verifier.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 047ac4b4703b..2a3955359156 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9912,6 +9912,8 @@ static int check_btf_line(struct bpf_verifier_env *env,
nr_linfo = attr->line_info_cnt;
if (!nr_linfo)
return 0;
+ if (nr_linfo * sizeof(struct bpf_line_info) > INT_MAX)
+ return -EINVAL;
rec_size = attr->line_info_rec_size;
if (rec_size < MIN_BPF_LINEINFO_SIZE ||
--
2.17.1
On Mon, Sep 6, 2021 at 11:04 PM Bixuan Cui <[email protected]> wrote:
>
> Commit 7661809d493b ("mm: don't allow oversized kvmalloc() calls") add the
> oversize check. When the allocation is larger than what kmalloc() supports,
> the following warning triggered:
>
> WARNING: CPU: 0 PID: 8408 at mm/util.c:597 kvmalloc_node+0x108/0x110 mm/util.c:597
> Modules linked in:
> CPU: 0 PID: 8408 Comm: syz-executor221 Not tainted 5.14.0-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:kvmalloc_node+0x108/0x110 mm/util.c:597
> Call Trace:
> kvmalloc include/linux/mm.h:806 [inline]
> kvmalloc_array include/linux/mm.h:824 [inline]
> kvcalloc include/linux/mm.h:829 [inline]
> check_btf_line kernel/bpf/verifier.c:9925 [inline]
> check_btf_info kernel/bpf/verifier.c:10049 [inline]
> bpf_check+0xd634/0x150d0 kernel/bpf/verifier.c:13759
> bpf_prog_load kernel/bpf/syscall.c:2301 [inline]
> __sys_bpf+0x11181/0x126e0 kernel/bpf/syscall.c:4587
> __do_sys_bpf kernel/bpf/syscall.c:4691 [inline]
> __se_sys_bpf kernel/bpf/syscall.c:4689 [inline]
> __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4689
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Reported-by: [email protected]
> Signed-off-by: Bixuan Cui <[email protected]>
> ---
> kernel/bpf/verifier.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 047ac4b4703b..2a3955359156 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -9912,6 +9912,8 @@ static int check_btf_line(struct bpf_verifier_env *env,
> nr_linfo = attr->line_info_cnt;
> if (!nr_linfo)
> return 0;
> + if (nr_linfo * sizeof(struct bpf_line_info) > INT_MAX)
> + return -EINVAL;
I might be missing something, but on 64-bit architecture this can't
overflow (because u32 is multiplied by fixed small sizeof()). And on
32-bit architecture if it overflows you won't catch it... So did you
mean to do:
if (nr_lifo > INT_MAX / sizeof(struct bpf_line_info))
return -EINVAL;
?
>
> rec_size = attr->line_info_rec_size;
> if (rec_size < MIN_BPF_LINEINFO_SIZE ||
> --
> 2.17.1
>
On 2021/9/9 12:57, Andrii Nakryiko wrote:
>> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
>> index 047ac4b4703b..2a3955359156 100644
>> --- a/kernel/bpf/verifier.c
>> +++ b/kernel/bpf/verifier.c
>> @@ -9912,6 +9912,8 @@ static int check_btf_line(struct bpf_verifier_env *env,
>> nr_linfo = attr->line_info_cnt;
>> if (!nr_linfo)
>> return 0;
>> + if (nr_linfo * sizeof(struct bpf_line_info) > INT_MAX)
>> + return -EINVAL;
> I might be missing something, but on 64-bit architecture this can't
> overflow (because u32 is multiplied by fixed small sizeof()). And on
> 32-bit architecture if it overflows you won't catch it... So did you
> mean to do:
>
> if (nr_lifo > INT_MAX / sizeof(struct bpf_line_info))
> return -EINVAL;
>
> ?
On 64-bit architecture, the value of INT_MAX may be equal to the 32-bit.
I get the same question: https://stackoverflow.com/questions/9257065/int-max-in-32-bit-vs-64-bit-environment
And 'if (nr_lifo > INT_MAX / sizeof(struct bpf_line_info))' is correct on 32-bit architecture ;)
Thanks,
Bixuan Cui
>