On Mon, Mar 18, 2019 at 12:47 PM Kevin Brodsky <kevin.brodsky@xxxxxxx> wrote: > > On 15/03/2019 19:51, Andrey Konovalov wrote: > > This patch is a part of a series that extends arm64 kernel ABI to allow to > > pass tagged user pointers (with the top byte set to something else other > > than 0x00) as syscall arguments. > > > > prctl_set_mm() and prctl_set_mm_map() use provided user pointers for vma > > lookups, which can only by done with untagged pointers. > > > > Untag user pointers in these functions. > > > > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > > --- > > kernel/sys.c | 14 ++++++++++++++ > > 1 file changed, 14 insertions(+) > > > > diff --git a/kernel/sys.c b/kernel/sys.c > > index 12df0e5434b8..8e56d87cc6db 100644 > > --- a/kernel/sys.c > > +++ b/kernel/sys.c > > @@ -1993,6 +1993,18 @@ static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data > > if (copy_from_user(&prctl_map, addr, sizeof(prctl_map))) > > return -EFAULT; > > > > + prctl_map->start_code = untagged_addr(prctl_map.start_code); > > + prctl_map->end_code = untagged_addr(prctl_map.end_code); > > + prctl_map->start_data = untagged_addr(prctl_map.start_data); > > + prctl_map->end_data = untagged_addr(prctl_map.end_data); > > + prctl_map->start_brk = untagged_addr(prctl_map.start_brk); > > + prctl_map->brk = untagged_addr(prctl_map.brk); > > + prctl_map->start_stack = untagged_addr(prctl_map.start_stack); > > + prctl_map->arg_start = untagged_addr(prctl_map.arg_start); > > + prctl_map->arg_end = untagged_addr(prctl_map.arg_end); > > + prctl_map->env_start = untagged_addr(prctl_map.env_start); > > + prctl_map->env_end = untagged_addr(prctl_map.env_end); > > As the buildbot suggests, those -> should be . instead :) You might want to check > your local build with CONFIG_CHECKPOINT_RESTORE=y. Oops :) > > > + > > error = validate_prctl_map(&prctl_map); > > if (error) > > return error; > > @@ -2106,6 +2118,8 @@ static int prctl_set_mm(int opt, unsigned long addr, > > opt != PR_SET_MM_MAP_SIZE))) > > return -EINVAL; > > > > + addr = untagged_addr(addr); > > This is a bit too coarse, addr is indeed used for find_vma() later on, but it is also > used to access memory, by prctl_set_mm_mmap() and prctl_set_auxv(). Yes, I wrote this patch before our Friday discussion and forgot about it. I'll fix it in v12, thanks! > > Kevin > > > + > > #ifdef CONFIG_CHECKPOINT_RESTORE > > if (opt == PR_SET_MM_MAP || opt == PR_SET_MM_MAP_SIZE) > > return prctl_set_mm_map(opt, (const void __user *)addr, arg4); >
