Описание
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix divide-by-zero in btf_struct_walk()
When an access goes past the struct and the last member is a flexible
array, btf_struct_walk() folds the offset back into a single element with
(off - moff) % t->size, but never checks that the element type has a size.
BTF takes an empty struct, so this in program BTF
/* event could be empty /
struct event {
#ifdef HAVE_TIMESTAMP
__u64 ts;
#endif
};
struct batch {
int nr;
struct event events[];
};
divides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that
is not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a
sleepable program.
Oops: divide error: 0000 [#1] SMP KASAN PTI
RIP: 0010:btf_struct_walk+0x53f/0x1570
Call Trace:
btf_struct_access+0x42a/0xcd0
check_ptr_to_btf_access+0x4dc/0x1160
check_mem_access+0x3a45/0x8740
check_load_mem+0x36a/0xd10
do_check_common+0x3ef0/0xb210
bpf_check+0x6d3b/0x8580
bpf_prog_load+0xf7c/0x2720
__sys_bpf+0xa83/0x3690
__x64_sys_bpf+0xc7/0x150
x64_sys_call+0x1f3f/0x27e0
do_syscall_64+0xe5/0x610
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Reject a zero-sized element type. The fixed array path in the same function
already bails out on the same thing:
btf_struct_walk()
...
/ skip empty array */
if (moff == mtrue_end)
continue;
msize /= total_nelems;
A flaw was found in the Linux kernel's BPF (Berkeley Packet Filter) subsystem. This vulnerability allows a local user to cause a Denial of Service (DoS) by crashing the kernel. When loading a specially crafted BPF program that accesses a structure with an empty flexible array member, the verifier attempts to compute offsets without checking for a zero element size, triggering a divide-by-zero error.
Отчет
This vulnerability is rated as having a Moderate impact because exploitation requires elevated administrative privileges, specifically CAP_BPF or CAP_SYS_ADMIN, to load the sleepable programs necessary to reach the affected verifier logic. Default Red Hat Enterprise Linux environments do not permit unprivileged users to load BPF programs or manipulate BTF objects. Consequently, the flaw is confined to a local denial of service via a kernel panic, without posing a risk to system confidentiality or integrity.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-8 | Fix deferred | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-9 | Fix deferred |
Показывать по
Дополнительная информация
Статус:
EPSS
4.4 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix divide-by-zero in btf_struct_walk() When an access goes past the struct and the last member is a flexible array, btf_struct_walk() folds the offset back into a single element with (off - moff) % t->size, but never checks that the element type has a size. BTF takes an empty struct, so this in program BTF /* event could be empty */ struct event { #ifdef HAVE_TIMESTAMP __u64 ts; #endif }; struct batch { int nr; struct event events[]; }; divides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that is not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a sleepable program. Oops: divide error: 0000 [#1] SMP KASAN PTI RIP: 0010:btf_struct_walk+0x53f/0x1570 Call Trace: <TASK> btf_struct_access+0x42a/0xcd0 check_ptr_to_btf_access+0x4dc/0x1160 check_mem_access+0x3a45/0x8740 check_load_mem+0x36a/0xd10 do_check_common+0x3ef0/0xb210 bpf_check+0x6d3b/0x8580 bpf_prog_load+0xf7c/0x2720 __s...
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix divide-by-zero in btf_struct_walk() When an access goes past the struct and the last member is a flexible array, btf_struct_walk() folds the offset back into a single element with (off - moff) % t->size, but never checks that the element type has a size. BTF takes an empty struct, so this in program BTF /* event could be empty */ struct event { #ifdef HAVE_TIMESTAMP __u64 ts; #endif }; struct batch { int nr; struct event events[]; }; divides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that is not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a sleepable program. Oops: divide error: 0000 [#1] SMP KASAN PTI RIP: 0010:btf_struct_walk+0x53f/0x1570 Call Trace: <TASK> btf_struct_access+0x42a/0xcd0 check_ptr_to_btf_access+0x4dc/0x1160 check_mem_access+0x3a45/0x8740 check_load_mem+0x36a/0xd10 do_check_common+0x3ef0/0xb210 bpf_check+0x6d3b/0x8580 bpf_p
In the Linux kernel, the following vulnerability has been resolved: b ...
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix divide-by-zero in btf_struct_walk() When an access goes past the struct and the last member is a flexible array, btf_struct_walk() folds the offset back into a single element with (off - moff) % t->size, but never checks that the element type has a size. BTF takes an empty struct, so this in program BTF /* event could be empty */ struct event { #ifdef HAVE_TIMESTAMP __u64 ts; #endif }; struct batch { int nr; struct event events[]; }; divides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that is not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a sleepable program. Oops: divide error: 0000 [#1] SMP KASAN PTI RIP: 0010:btf_struct_walk+0x53f/0x1570 Call Trace: <TASK> btf_struct_access+0x42a/0xcd0 check_ptr_to_btf_access+0x4dc/0x1160 check_mem_access+0x3a45/0x8740 check_load_mem+0x36a/0xd10 do_check_common+0x3ef0/0xb210 bpf_check+0x6d3b/0x8580 bp...
EPSS
4.4 Medium
CVSS3