fs/proc: kcore: use kcore_list type to check for vmalloc/module address

BugLink: https://bugs.launchpad.net/bugs/1702749
Instead of passing each start address into is_vmalloc_or_module_addr()
to decide whether it falls into either the VMALLOC or the MODULES region,
we can simply check the type field of the current kcore_list entry, since
it will be set to KCORE_VMALLOC based on exactly the same conditions.

As a bonus, when reading the KCORE_TEXT region on architectures that have
one, this will avoid using vread() on the region if it happens to intersect
with a KCORE_VMALLOC region. This is due the fact that the KCORE_TEXT
region is the first one to be added to the kcore region list.

Reported-by: Tan Xiaojun <tanxiaojun@huawei.com>
Tested-by: Tan Xiaojun <tanxiaojun@huawei.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from commit 737326aa510b5f7d2f38ded739914a9d5e4e4cea)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 0b80ad87b4d6699076317eae8b08eda14fa74c96..dfd10980d7d5a05ec2f3859e45fa0690c713d54d 100644 (file)
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -500,7 +500,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
                if (&m->list == &kclist_head) {
                        if (clear_user(buffer, tsz))
                                return -EFAULT;
-               } else if (is_vmalloc_or_module_addr((void *)start)) {
+               } else if (m->type == KCORE_VMALLOC) {
                        vread(buf, (char *)start, tsz);
                        /* we have to zero-fill user buffer even if no read */
                        if (copy_to_user(buffer, buf, tsz))