On Wed, Apr 14, 2021 at 7:52 AM syzbot <syzbot+08062910481610616...@syzkaller.appspotmail.com> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: b2b3d18f riscv: Make NUMA depend on MMU > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git > fixes > console output: https://syzkaller.appspot.com/x/log.txt?x=12b59d16d00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=81b3e7c68dad6e > dashboard link: https://syzkaller.appspot.com/bug?extid=0806291048161061627c > userspace arch: riscv64 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+08062910481610616...@syzkaller.appspotmail.com > > ================================================================== > BUG: KASAN: use-after-free in walk_stackframe > arch/riscv/kernel/stacktrace.c:60 [inline] > BUG: KASAN: use-after-free in get_wchan+0x156/0x196 > arch/riscv/kernel/stacktrace.c:136 > Read of size 8 at addr ffffffe0058e3d90 by task syz-executor.0/4667 > > CPU: 1 PID: 4667 Comm: syz-executor.0 Not tainted > 5.12.0-rc5-syzkaller-00721-gb2b3d18fc20e #0 > Hardware name: riscv-virtio,qemu (DT) > Call Trace: > [<ffffffe000009706>] walk_stackframe+0x0/0x23c arch/riscv/kernel/traps.c:201 > [<ffffffe002a5f182>] dump_backtrace+0x40/0x4e > arch/riscv/kernel/stacktrace.c:113 > [<ffffffe002a5f1b2>] show_stack+0x22/0x2e arch/riscv/kernel/stacktrace.c:118 > [<ffffffe002a68a3e>] __dump_stack lib/dump_stack.c:79 [inline] > [<ffffffe002a68a3e>] dump_stack+0x148/0x1d8 lib/dump_stack.c:120 > [<ffffffe0003bc802>] print_address_description.constprop.0+0x52/0x31e > mm/kasan/report.c:232 > [<ffffffe0003bcd24>] __kasan_report mm/kasan/report.c:399 [inline] > [<ffffffe0003bcd24>] kasan_report+0x16e/0x18c mm/kasan/report.c:416 > [<ffffffe0003bd588>] check_region_inline mm/kasan/generic.c:180 [inline] > [<ffffffe0003bd588>] __asan_load8+0x6e/0x80 mm/kasan/generic.c:253 > [<ffffffe000009a98>] walk_stackframe arch/riscv/kernel/stacktrace.c:60 > [inline]
If it's walking the stack of another task, then it needs to use READ_ONCE_NOCHECK. See x86/arm64/s390 for examples: https://elixir.bootlin.com/linux/v5.12-rc7/A/ident/READ_ONCE_NOCHECK > [<ffffffe000009a98>] get_wchan+0x156/0x196 arch/riscv/kernel/stacktrace.c:136 > [<ffffffe000553364>] proc_pid_wchan+0x48/0xa4 fs/proc/base.c:390 > [<ffffffe000554458>] proc_single_show+0x9c/0x13c fs/proc/base.c:774 > [<ffffffe00045000c>] seq_read_iter+0x2e0/0x8f2 fs/seq_file.c:227 > [<ffffffe00045081e>] seq_read+0x200/0x298 fs/seq_file.c:159 > [<ffffffe0003f9210>] vfs_read+0x108/0x2ac fs/read_write.c:494 > [<ffffffe0003f9724>] ksys_read+0xb4/0x1b8 fs/read_write.c:634 > [<ffffffe0003f9850>] __do_sys_read fs/read_write.c:644 [inline] > [<ffffffe0003f9850>] sys_read+0x28/0x36 fs/read_write.c:642 > [<ffffffe000005572>] ret_from_syscall+0x0/0x2 > > The buggy address belongs to the page: > page:ffffffcf0216b8c0 refcount:0 mapcount:0 mapping:0000000000000000 > index:0x0 pfn:0x85ae3 > flags: 0xffe000000000000() > raw: 0ffe000000000000 ffffffcf0216b8c8 ffffffcf0216b8c8 0000000000000000 > raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffffffe0058e3c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffffffe0058e3d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > >ffffffe0058e3d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ^ > ffffffe0058e3e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffffffe0058e3e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkal...@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > -- > You received this message because you are subscribed to the Google Groups > "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to syzkaller-bugs+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/syzkaller-bugs/0000000000009862e005bfe859c8%40google.com.