syzbot report a slab-out-of-bounds in __rb_map_vma. [1] 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. [1] 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 Reported-by: syzbot+345e4443a21200874...@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=345e4443a21200874b18 Tested-by: syzbot+345e4443a21200874...@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis <eada...@qq.com> --- kernel/trace/ring_buffer.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 7e257e855dd1..15c43d7415d5 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7019,6 +7019,9 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); nr_subbufs = cpu_buffer->nr_pages + 1; /* + reader-subbuf */ + if (((nr_subbufs + 1) << subbuf_order) < pgoff) + return -EINVAL; + nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ nr_vma_pages = vma_pages(vma); -- 2.47.0
