On Mon, Apr 10, 2023 at 09:45:02AM +0800, xiaosong.ma wrote: > perform the check in dump_mapping() to print warning info and avoid crash with invalid non-NULL page->mapping. > For example, a panic with following backtraces show dump_page will show wrong info and panic when the bad page > is non-NULL mapping and page->mapping is 0x80000000000. > > crash_arm64> bt > PID: 232 TASK: ffffff80e8c2c340 CPU: 0 COMMAND: "Binder:232_2" > #0 [ffffffc013e5b080] sysdump_panic_event$b2bce43a479f4f7762201bfee02d7889 at ffffffc0108d7c2c > #1 [ffffffc013e5b0c0] atomic_notifier_call_chain at ffffffc010300228 > #2 [ffffffc013e5b2c0] panic at ffffffc0102c926c > #3 [ffffffc013e5b370] die at ffffffc010267670 > #4 [ffffffc013e5b3a0] die_kernel_fault at ffffffc0102808a4 > #5 [ffffffc013e5b3d0] __do_kernel_fault at ffffffc010280820 > #6 [ffffffc013e5b410] do_bad_area at ffffffc01028059c > #7 [ffffffc013e5b440] do_translation_fault$4df5decbea5d08a63349aa36f07426b2 at ffffffc0111149c8 > #8 [ffffffc013e5b470] do_mem_abort at ffffffc0100a4488 > #9 [ffffffc013e5b5e0] el1_ia at ffffffc0100a6c00 > #10 [ffffffc013e5b5f0] __dump_page at ffffffc0104beecc This doesn't show a crash in dump_mapping(), it shows a crash in __dump_page(). > diff --git a/fs/inode.c b/fs/inode.c > index f453eb5..c9021e5 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -564,7 +564,8 @@ void dump_mapping(const struct address_space *mapping) > * If mapping is an invalid pointer, we don't want to crash > * accessing it, so probe everything depending on it carefully. > */ > - if (get_kernel_nofault(host, &mapping->host) || > + if (get_kernel_nofault(mapping, &mapping) || > + get_kernel_nofault(host, &mapping->host) || This patch makes no sense. Essentially, you're saying mapping = &mapping which is obviously wrong.
