On Wed, 5 Sep 2018 00:38:22 +0200 Dominique Martinet <asmadeus@xxxxxxxxxxxxx> wrote:
> The 'm' kcore_list item could point to kclist_head, and it is incorrect to
> look at m->addr / m->size in this case.
> There is no choice but to run through the list of entries for every address
> if we did not find any entry in the previous iteration
>
> Reset 'm' to NULL in that case at Omar Sandoval's suggestion.
>
> ...
>
> --- a/fs/proc/kcore.c
> +++ b/fs/proc/kcore.c
> @@ -464,6 +464,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
> ret = -EFAULT;
> goto out;
> }
> + m = NULL;
> } else if (m->type == KCORE_VMALLOC) {
> vread(buf, (char *)start, tsz);
> /* we have to zero-fill user buffer even if no read */
lgtm. Let's add a nice little why-were-doing-this?
--- a/fs/proc/kcore.c~proc-kcore-fix-invalid-memory-access-in-multi-page-read-optimization-v3-fix
+++ a/fs/proc/kcore.c
@@ -464,7 +464,7 @@ read_kcore(struct file *file, char __use
ret = -EFAULT;
goto out;
}
- m = NULL;
+ m = NULL; /* skip the list anchor */
} else if (m->type == KCORE_VMALLOC) {
vread(buf, (char *)start, tsz);
/* we have to zero-fill user buffer even if no read */
_
