2021-09-11 01:01:46

by Bixuan Cui

Subject: [PATCH -next v2] bpf: Add oversize check before call kvcalloc()

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]>
---
Chang in v2:
* Change 'if (nr_linfo * sizeof(struct bpf_line_info) > INT_MAX)' to
'if (nr_lifo > INT_MAX / sizeof(struct bpf_line_info))'.

kernel/bpf/verifier.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a0dd972d5b41..de006552be8a 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 > 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

2021-09-13 02:27:58

by Yonghong Song

Subject: Re: [PATCH -next v2] bpf: Add oversize check before call kvcalloc()

On 9/10/21 5:55 PM, Bixuan Cui 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]>

Acked-by: Yonghong Song <[email protected]>