On Mon, Mar 18, 2019 at 12:47 PM Kevin Brodsky kevin.brodsky@arm.com 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@google.com
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);