CVE-2024-56368

In the Linux kernel, the following vulnerability has been resolved:

ring-buffer: Fix overflow in __rb_map_vma

An overflow occurred when performing the following calculation:

nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff;

Add a check before the calculation to avoid this problem.

syzbot reported this as a slab-out-of-bounds in __rb_map_vma:

BUG: KASAN: slab-out-of-bounds in __rb_map_vma+0x9ab/0xae0 kernel/trace/ring_buffer.c:7058

Read of size 8 at addr ffff8880767dd2b8 by task syz-executor187/5836

CPU: 0 UID: 0 PID: 5836 Comm: syz-executor187 Not tainted 6.13.0-rc2-syzkaller-00159-gf932fb9b4074 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024

Call Trace:

<TASK>

__dump_stack lib/dump_stack.c:94 [inline]

dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120

print_address_description mm/kasan/report.c:378 [inline]

print_report+0xc3/0x620 mm/kasan/report.c:489

kasan_report+0xd9/0x110 mm/kasan/report.c:602

__rb_map_vma+0x9ab/0xae0 kernel/trace/ring_buffer.c:7058

ring_buffer_map+0x56e/0x9b0 kernel/trace/ring_buffer.c:7138

tracing_buffers_mmap+0xa6/0x120 kernel/trace/trace.c:8482

call_mmap include/linux/fs.h:2183 [inline]

mmap_file mm/internal.h:124 [inline]

__mmap_new_file_vma mm/vma.c:2291 [inline]

__mmap_new_vma mm/vma.c:2355 [inline]

__mmap_region+0x1786/0x2670 mm/vma.c:2456

mmap_region+0x127/0x320 mm/mmap.c:1348

do_mmap+0xc00/0xfc0 mm/mmap.c:496

vm_mmap_pgoff+0x1ba/0x360 mm/util.c:580

ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:542

__do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]

__se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]

__x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82

do_syscall_x64 arch/x86/entry/common.c:52 [inline]

do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83

entry_SYSCALL_64_after_hwframe+0x77/0x7f

The reproducer for this bug is:

------------------------8<-------------------------

#include <fcntl.h>

#include <stdlib.h>

#include <unistd.h>

#include <asm/types.h>

#include <sys/mman.h>

int main(int argc, char **argv)

{

int page_size = getpagesize();

int fd;

void *meta;

system("echo 1 > /sys/kernel/tracing/buffer_size_kb");

fd = open("/sys/kernel/tracing/per_cpu/cpu0/trace_pipe_raw", O_RDONLY);

meta = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, page_size * 5);

}

------------------------>8-------------------------